.??_  Files ending in "_" are often compressed install files of the same
          name (e.g., .EX_ expands to .EXE, .DL_ expands to .DLL, etc.)
  .S    Assembler Source Code
        Scheme Source Code
  .S$$  Temporary Sort File
  .S$N  Mindstore Digital Wallet File (M$A$W$.S$N)
  .S??  RAR Compressed File (?? can be 01 to 99 after .R99)
  .S01  WordPerfect Distribution File
  .S02  WordPerfect Distribution File
  .S03  WordPerfect Distribution File
  .S16  Sigames File
  .S19  Motorola Assembly-Language Program ASCII-HEX Data File
  .S28  Genesis or Sega32X Rom Image
  .S2P  Sonnet File
  .S3D  EverQuest File
  .S3I  ScreamTracker v3 Instrument
  .S3M  ScreamTracker v3 Module
        ScreamTracker v3 Sound File
  .S4T  Patent Application Specification Authoring Tool (PASAT) File
  .S4W  Patent Application Specification Authoring Tool (PASAT) File
  .S8   Simul8 Simulation
  .SA1  Panasonic e-wear MP3 Player File
  .SA4  STABCAL (stability calculation for aqueous systems) File
  .SA8  Street Atlas File
  .SAB  ModelMaker File (3D scanner)
  .SAC  Adobe Shared Asset Catalog
  .SAD  Serveron Analyzer Data File
        Electronic Arts Black & White Game Sound File  [Dragon UnPACKer]
  .SAF  MusicMatch Jukebox Secure Audio File
  .SAH  SETI@Home Data File
  .SAK  Software Administration Kit (Customer Tracking for Shareware Authors)
  .SAL  Soritec Data
  .SAM  Ami Pro Text File
        Map File (HOSTS.SAM - Maps IP addresses to machine names)
        Signed 8-bit Sample Data
        CalTech PaleoMag Data File
  .SAN  The Curse of Monkey Island Movie File
        Legacy of Kain Series Game File
  .SAR  Phoenix Server Applications Standard Distribution Format (.JAR file in special directory)
        Sons Of The American Revolution Family Tree Creator Data
        Saracen Paint  [XnView]
  .SAS  SAS System File (statistical anaysis)
  .SAT  ACIS Solid Model (any ACIS-based CAD program)
  .SAV  Backup
        Saved File (various)
        Saved Configuration Info (various)
  .SB   Audio File
        Raw Signed Byte (8-bit) Data
  .SBD  Storyboard Editor Storyboard
  .SBF  Superbase 95 File
  .SBI  Sound Blaster Instrument File
  .SBK  Emu SoundFont v1.x Bank Files
        Superbase 95 File
        Creative Labs SB AWE 32
        Statfoot32 Soccer League Tracking File
        SWiSH Backup File (Flash animation)
  .SBL  Shockwave Flash Object
  .SBM  Hello Network HelloCombined Media Player (MultiPlatform Streaming Media Player)
  .SBN  ArcView Optional Shape File (GIS-related)
  .SBP  Superbase DML Program
        SetupBuilder Professional Projects File
  .SBR  Source Browser Support File
  .SBS  SWAT HRU Output File (river basin scale model)
  .SBT  Superbase Record Notes
  .SBW  Savings Bonds Wizard (U.S. Treasury program)
  .SBX  ArcView Optional Shape File (GIS-related)
  .SC   Framework Screen Driver
        Paradox Source Code
        Ingres Embedded SQL/C Source File
  .SC?  ColoRIX Image (? can vary)  [XnView]
  .SC2  Sample Cell
        SimCity 2000 City
        II PC Instrument
        Schedule+ File
        SAS Catalog
        MSX 2 Screen  [XnView]
  .SC3  Harvard Screen Driver (Harvard Graphics taken over by Serif)
        SimCity 3000 File
        dBase Screen Mask File
  .SC4  RollerCoaster Tycoon Scenario
        Creative NOMAD MP3 Manager
  .SCA  SCA Datafile
        Scala InfoChannel Script
  .SCANNER  Scanner Output File (usually a bitmap image) - Note: I've had reports of this but cannot confirm
  .SCB  Scala InfoChannel Published Script
        System Cleaner
  .SCC  Text File
        Stamp Collector's Girl Friday Catalog File
        Source Safe File
  .SCD  Graphic (SCODL Scan Conversion Object Description Language)
        Schedule+ File
        TurboTax Schedule File
  .SCE  SoftCuisine Data Exchange File
  .SCF  Windows Explorer Command
        Symphony Spell Checker Configuration
        Photo Soap2 File
        ScoreMaker Multimedia Show
  .SCG  Septerra Core Saved Game
  .SCH  Schedule+ File
        EAGLE Schematic File
        OrCad Schematics File
        P-CAD Schematic File
        Xlinix Foundation Schematic
        XML Schema
  .SCI  ScanVec Inspire File
        ColoRIX Image  [XnView]
        SciFax FAX  [XnView]
        System Configuration Data
  .SCL  SCALA Scale
  .SCM  SchematicMaker (Topanga Software) File
        ICQ Sound Compressed Sound Scheme
        Scheme Program
        ScreenCam Movie
        Starcraft Map File
  .SCN  Compressed Screen format
        TrueSpace2 Scene
        Pinnacle Studio Scene File (Info about scenes found in same-named .AVI)
        Scenario File For Many Games Including: Age of Empires, Age of Empires: Rise of Rome,
          Seven Kingdoms, SimCity Classic, SimCity 2000, SimCity 3000, SimCity 3000 Unlimited
  .SCO  High Score (various)
        ObjectJ AuthorJ Saved Lesson
  .SCP  Script (various)
  .SCR  Faxview Fax
        Screen Saver
        Procomm Plus Screen Snapshot File
        Script (various)
        DOS DEBUG Input File (can be any extension but often .SCR)
        LocoScript Screen Font File
        Statistica Scrollsheet
        Movie Master Screenplay (DOS software replaced by Hollywood Screenplay)
        Sun Raster Graphic  [XnView]
  .SCS  StuffIt Saved Criteria
        OzWin CompuServe E-mail/Forum Access SYSOP File
        Samsung Q105 Phone Screen Saver
        Omron CX-Supervisor (Factory Automation)
  .SCT  Foxpro Screen
        PC Tools Script Tools
        Scitex Continuous Tone Bitmap  [XnView]
        SAS Catalog
        OzWin CompuServe E-mail/Forum Access Forum Section Names
        Windows Script Component
        Lotus Screen Capture Text
  .SCV  ScanVec CASmate File
  .SCW  Score Writer Document (music score)
  .SCX  MS FoxPro Screen File
        ColorIRX Image File  [XnView]
        Stanford Chart
        Starcraft Map File
  .SCY  ReaGeniX Security File
  .SD   Sound Designer I Audio
  .SD0  Dali Raw File  [XnView]
  .SD1  Dali Raw File  [XnView]
  .SD2  Sound Designer II Flattened File
        Sound Designer II Data Fork
        SAS Database
        Dali Raw File  [XnView]
  .SD7  Daktronics Venus 7000 Electronic Sign Schedule
  .SD!  OzWin CompuServe E-mail/Forum Access Custom Messsage Search Online
  .SDA  StarOffice Drawing
        Fidonet Software Distribution Network Archive Description
        SoftCuisine Data Archive
        PGP Encrypted Executable
  .SDB  Simply Accounting File
        Group Mail Subscriber Plug-in File
        MS Win2000 Security Configuration and Analysis Database
  .SDC  StarOffice Spreadsheet
  .SDD  StarOffice Presentation
  .SDF  Standard Data Format
        Standart-Delay-Format (Chip design gatelevel-delay data exchange...
           e.g., Synopys to Modelsim)
        Schedule Data File
        System File Format
        Autodesk MapGuide Spatial Data Files
  .SDG  Star Office Gallery  [XnView]
  .SDI  Fidonet Software Distribution Network Info
  .SDK  Roland S-series Floppy Disk Image
        Autosketch Drawing
  .SDL  SmartDraw Library
        OzWin CompuServe E-mail/Forum Access Custom Messsage Search
  .SDN  Shell Archive
        Fidonet Software Distribution Network Compressed Archive
  .SDOC  Sealed Word File [Unsealer]
  .SDP  QuickTime Session Description Protocol File (resides on server; contains info about format, timing, & authorship of streamed media)
        Real Player File
  .SDR  SmartDraw Drawing
  .SDS  StarOffice Chart
        Raw Midi Sample Dump Standard File
  .SDT  SmartDraw Template
        Dungeon Keeper 2 Archive  [Dragon UnPACKer]
        Theme Park World Archive  [Dragon UnPACKer]
  .SDV  Semicolon Divided Values File
  .SDW  StarOffice Text
        Raw Signed DWord (32-bit) Data
        Lotus WordPro Graphic
  .SDX  Midi Sample Dump Standard Files Compacted by SDX
  .SDV  Pinnacle Studio DV Video Editing Project
  .SE   ScopeEdit Project File
  .SEA  Macintosh Compressed Archive File  [StuffIt]
  .SEB  Franklin eBookMan Format
  .SEC  Compressed Archive File
        Disney Animation Studio Secured Animation File
        PGP Secret Key Ring
        MP3 Music File (unverified)
  .SEE  LISCAD Plus File
  .SEF  Steganos Encrypted File
  .SEG  Compressed File Segment
  .SEL  PaintShop Pro Selection File
  .SEM  ZX Spectrum-Emulator Snapshot
  .SEO  ScopeEdit Object File
  .SEP  TIFF Bitmap Separation
  .SEQ  Atari Animation File
        TestStand Sequence File
        Bubble Chamber Sequential Instruction File
        Chromeleon Sequence List
        LifeForm File
        Stad File  [XnView]
        Power Tracks Pro Music Sequencer File
  .SEQU  Acrobat Sequence File
  .SES  Digital Audio Editor File
        Clarion Modula-2 Session Data
        Hummingbird Exceed X-Session
        Shadow Security Scanner Session
  .SET  Driver Set
        Image Settings
        Backup File Set
        Configuration (various)
  .SEU  Serials 2000 Encrypted S2K Update
  .SEW  Janome (New Home) Sewing Machine File
        Embroidery Design File [possibly read with Melco Sizer Software]
  .SEX  Urban Chaos Game File
  .SF   Sound File [Linux Player]
        OS/2 WPS Attribute Storage
        IRCAM SoundFile
        Powerhouse Subfile Data File (contents defined by .SFD dictionary)
  .SF2  Emu SoundFont v2.0 File
        Creative Labs Soundfont 2.0 Bank File
  .SFA  Sonic Foundry Video Editor Audio File
  .SFD  SoundStage Sound File Data
        Powerhouse Subfile Dictionary (describes .SF file contents)
  .SFE  Split Files Shell Extension
  .SFF  Fritz Fax-Print File
        Stage Scene File
        Structured Fax Format  [XnView]
  .SFI  Ventura Printer Font
        SoundStage Sound File Info
        SIS Framegrabber Graphics
  .SFK  Sound Forge Peak Data File
  .SFL  Ventura Printer Font
        LaserJet Landscape Font
  .SFM  DART Pro 98 Soundtree Structure
  .SFN  SPX Font
  .SFP  Ventura Printer Font
        LaserJet Portrait Font
  .SFR  Sonic Foundry Sample Resource
  .SFS  StarOffice Frame
        PCL 5 Scalable Font
  .SFT  Chiwriter Screen Font
  .SFV  QuickSFV/WinSFV Checksum File
        Easy SFV Creator
        fsum (free command line checksum file creator/verifier)
  .SFW  Seattle Film Works File (Actually MGI PhotoSuite File) [Filmworks Viewer] [XnView] [IrfanView]
  .SFX  Self-extracting Archive
  .SG   ABC Snap Graphics User File
  .SG1  Stanford Graphics
  .SGA  SEG-A Seismic Data Format (SEG=Society of Exploration Geophysicists) [data processing: Lacey]
  .SGB  SEG-B Seismic Data Format (SEG=Society of Exploration Geophysicists) [data processing: Lacey]
  .SGC  SEG-C Seismic Data Format (SEG=Society of Exploration Geophysicists) [data processing: Lacey]
  .SGD  SameGame Data File
        SEG-D Seismic Data Format (SEG=Society of Exploration Geophysicists) [data processing: Lacey]
  .SGF  Smart Game Format
        StarWriter Document
        Sonique Document with Graphics
  .SGI  Silicon Graphics IRIS Graphic File  [XnView] [IrfanView]
  .SGIF  Sealed GIF File [Unsealer]
  .SGL  StarOffice Master Document
  .SGM  SoftQuad XMetaL File
  .SGN  Sierra Print Artist Sign
  .SGO  SansGUI Object Library File (compiled class definitions and objects for building models)
  .SGP  Statgraphics Plus Statistics
        SansGUI Project Model File (model configurations and input parameters defined by simulation users for simulation runs)
  .SGS  SansGUI Schema Definition File (class schemas defined for a simulator)
  .SGT  Hitman Game Sound File
        DirectMusic Producer
        Signature Keyboard Macro
  .SGU  GJDV Word Processor Keyboard Definition File
        Band-in-a-Box File
  .SGW  Settler GOLD for Windows Data File
  .SGY  SEG-Y Seismic Data Format (SEG=Society of Exploration Geophysicists) [data processing: Lacey]
  .SH   UNIX shar Archive File
        UNIX/LINUX Shell Script
  .SH3  Harvard Presentation (Harvard Graphics taken over by Serif)
  .SHADER  Script File for Game Textures (ASCII file--but, it's easier if you use Photoshop)
  .SHB  Corel Background File
        Document Shortcut File
  .SHD  Print Spooler Shadow File
  .SHE  Medusa CAD File [Outdated. Medusa CAD sold by PTC to CAD Schroer.]
  .SHG  Hotspot Editor Hypergraphic
  .SHIFTS  ARIA PIPP Chemical Shifts File
  .SHK  Apple II Compressed Archive File
  .SHM  WordPerfect Shell Macro
  .SHN  Shorten Audio Compression File [Additional]
  .SHP  3D Studio Shapes File
        GIS Software Geographic Shape File  [GIS info]
		  (ArcView, et.al.) (JShape/FShape)
        3D Modeling File (various)
  .SHR  UNIX shar Archive File
  .SHS  Shell Scrap Object File
  .SHTM  HTML File Containing Server Side Directives
  .SHTML  HTML File Containing Server Side Directives
  .SHW  Corel Presentation
        WordPerfect Slide Show
        Show File
  .SHX  AutoCAD Shape Entities
        GIS Software Geographic Shape Index File  [GIS info]
		  (ArcView, et.al.) (JShape/FShape)
  .SI   SoftImage Image File  [XnView]
  .SIB  Sibelius Music File
  .SID  Commodore64 Music File [Player] MIME type: audio/prs.sid
        LizardTech MrSID Photo [Free plug-in viewer]
  .SIF  Windows NT Setup File
        Autodesk Spatial Index File
  .SIG  Signature File
        Print Shop Sign File
  .SIK  Backup File
  .SIM  Simulation (various) (e.g. Setup for Nascar4)
        Aurora  [XnView]
        PowerDVD File (powerdvd.sim)
        PC Finder 2002C (Trace stolen computers)
  .SIR  SIR (Scientific Information Retrieval) Database (ver 1-3)
        BYU SIR  [XnView]
        Solitaire Image Recorder  [XnView]
  .SIS  SymbianOS Installer File (application installation archive)
  .SIT  StuffIt Compressed Archive File (Multiple platforms)
        Sinclair Snapshot
  .SITHQX  StuffIt Compressed Archive File (Multiple platforms)
  .SIZ  Oracle 7 Configuration
  .SJ1  Sega SJ-1 DIGIO  [XnView]
  .SJF  Split Files Shell Extension
  .SJPG  Sealed JPEG File [Unsealer]
  .SJX  Seljax Estimating and 3D Design
  .SKA  PGP Secret Keyring
  .SKB  QuickPOS (Point-Of-Sale) Standard Keyboard Layout File
  .SKCARD  Sidekick File (now a discoutinued product of Starfish which maintains a FAQ)
  .SKD  WinOrbit File
        AutoSketch File
        VEX Format File
        Max Payne Model File
  .SKF  Autosketch
  .SKL  Authorware Resource
  .SKN  FileWrangler/SecurDesk!/ImageForge Graphic Skin
        eRocket eBook Skin
        The Sims (Maxis) 3D Body Mesh Skin Data
        Skantek  [XnView]
  .SKR  Microsoft ScriptIt
  .SKY  ActiveSky Movie Clips for Palm OS
  .SKZ  coverXP Skin File
  .SL   S-Lang Program File
        PACT's Save Layout
        EROSION 3D Soil Parameters [Format (pdf)]
  .SLB  AutoCAD Slide Library
  .SLC  Telix Compiler SALT Script
  .SLD  AutoCAD Slide
        STABCAL (stability calculation for aqueous systems) File
  .SLDASM  Solidworks Assembly File
  .SLDDRW  Solidworks File
  .SLDLFP  Solidworks File
  .SLDPRT  Solidworks File
  .SLF  Shopcalc List File (Cabinet Door & Drawer Cutting List Calculator)
        Suppose Stand List File
        SLIDE: Scene Language for Interactive Dynamic Environments File
        SuperLink Folder Manager for Readers
        Mail Warden
        Segment Layout File (IMS Database related)
        SortWizard Export Format
  .SLG  Chromeleon Audit Trail
  .SLI  MagiCorp Side Service Slide
  .SLK  Data Exchange File (Symbolic Link - Often used by Excel)
        Timeslips Lock File
  .SLL  Sound File
  .SLM  Microsoft Visual FoxPro
  .SLP  Timeslips Data File
  .SLT  Telix SALT Script Application
        Super Level Loader Snapshot [Format]
  .SLW  Settler LITE for Windows Data File
  .SLY  Parts of a Lilypond Guitar File (ASCII text)
  .SM   Smalltalk Program File
        SoftSpoken Mailer Mailing List
        ScriptMaker Script
        Simentor Data File
        Samna Word Text File
  .SM3  DataCAD Symbol File
  .SMC  Super Nintendo Game-console ROM Image  [See ZNES or SNES9x]
  .SMCL  Stata Saved Formatted Logs
  .SMD  StarOffice Mail
        Sega Genesis/Mega Drive Emulator
  .SMF  StarOffice Formula
        Smartfax Fax
  .SMI  RealPlay SMIL File
        Self Mounting Image File (Apple Macintosh)
  .SMIL  Synchronized Multimedia Integration Language [RealPlay]
  .SMK  Smacker Compressed File
  .SML  Simple Markup Language
  .SMM  Ami Pro Macro
  .SMOV  Sealed QuickTime Movie File [Unsealer]
  .SMP  Sample or Samplevision Format
        Sound File [Linux Player]
        Ad Lib Gold Sample
        PhotoImpact Gallery File
  .SMP3  Sealed MP3 File [Unsealer]
  .SMRD  Adobe InDesign Import/Export Filter
  .SMS  MS Package Definition File (used now in place of .PDF)
        Sega Master System Emulator
  .SMT  HiPer-Six Memo File
        SmartWare II Text File
  .SMWT  Adobe InDesign Import/Export Filter
  .SMX  Statistica Matrix Spreadsheet
  .SNA  Mirage Microdrive Snapshot [Format]
  .SNAP  Mirage Microdrive Snapshot [Format]
  .SNAPSHOT  Mirage Microdrive Snapshot [Format]
  .SNB  SigmaStat File
  .SNC  Act! Modem Sync File
  .SND  Sound Clip  [IrfanView]
        Raw Unsigned PCM Data
        AKAI MPC-series Sample
        NeXT Sound
        Macintosh Sound Resource
        Heroes of Might & Magic 3 Archive  [Dragon UnPACKer]
  .SNES  Super Nintendo Game File (unverified)
  .SNG  Midisoft Studio MIDI Song
  .SNI  MDK Archive  [Dragon UnPACKer]
  .SNK  Strong Name Key File (part of the .NET architecture)
  .SNM  Netscape Mail
  .SNO  SNOBOL Program File
        Siege Editor Node
  .SNP  Snapview Shapshot
        MS Access Snapshop [Viewer] (page of Access report preserves layout, etc.)
        CoffeeCup HTML Editor Snippet
        Computer Eyes Video Output
  .SNT  MS Sticky Notes (accessory for Windows XP tablet PC edition - due end 2002)
  .SNX  Second Nature Software Graphic
        Mirage Microdrive Snapshot Extended Version
        StarCraft Saved File
  .SO   Oberlin DRAGN Graph Algorithm
  .SOA  Sage MAS 90 Accounting Software File
  .SOC  SociometryPlus Sociometric Group
  .SOE  Shadows of the Empire
  .SOL  Game Solution (various games)
  .SOM  Paradox Sort Info
        Quattro Pro Network Serial Numbers
  .SOU  SB Studio II Sound
  .SP   Splint Compressed Archive File (UNIX)
        VgaSpec/Spectrum Snapshot [Format]
  .SPC  Multiplan Program
        WordPerfect Temp File
        Interact Shark Port Code Save (SharkPort=code/game save xfer kit for PlayStation 2)
        SNES Audio file
        PKCS #7 Certificate
        Spectrum 512 Compressed File  [XnView]
  .SPD  Harvard Bitstream Typefaces (Harvard Graphics taken over by Serif)
        PostScript Printer
        Speech Data File
        Speedo Scalable Font
  .SPDF  Sealed PDF File  [Unsealer]
  .SPF  Site Publisher Profile
        EnerGraphics Slide Presentation
  .SPG  Sprint Glossary
  .SPH  SDR99 Speech Recognition Task SPHERE Waveform
  .SPI  Scanner Graphics
  .SPJ  Site Publisher Project File
  .SPL  Compressed Archive File
        Printer Spool File  [MS Knowledgebase Article]
        Sprint Printer Driver
        Sample File
        Spell Checker
        Digitrakker Sample (by n-FaCToR)
        Shockwave Flash Object
        Split Files Shell Extension
        Infinity Engine Game Spell
  .SPM  WordPerfect File
  .SPN  WordPerfect Distribution File
  .SPO  SPSS Statistical Program
  .SPP  Sprint Printer File
        Serif PhotoPlus Native Format File
  .SPPT  Sealed PowerPoint File [Unsealer]
  .SPR  Sprint Document Letter
        Foxpro Generated Screen Program
  .SPS  Sprint Screen Driver
        SharkPort File (transfers game saves from computer to PlayStation2)
        VAX/VMS Source Code
        Spectrum 512 Smooshed File  [XnView]
  .SPT  SPITBOL Program File
        Liquid Audio Player Secure Portable Track File
        MITAC Disk/System Management Utility Pack Support File
  .SPU  Spectrum 512  [XnView]
  .SPW  SigmaPlot Worksheet
  .SPX  Foxpro Compiler Screen Program
        Screen Peace Extension
  .SPZ  Spazz3d VRML File
  .SQ7  Daktronics Venus 7000 Electronic Sign Sequence
  .SQB  SyQuest Backup
  .SQC  Structured Query Language Common Code File  [SQL]
  .SQL  Structured Query Language Data  [SQL]
  .SQM  Operation Flashpoint Mission
  .SQR  Structured Query Language Program File  [SQL]
  .SQS  Operation Flashpoint Script
  .SQZ  Compressed Archive File
  .SR   Sun Raster Graphic  [XnView]
  .SR1  SIR (Scientific Information Retrieval) Database
  .SR2  SIR (Scientific Information Retrieval) Database
        Omron CX-Supervisor (Factory Automation)
  .SR3  SIR (Scientific Information Retrieval) Database
  .SR4  SIR (Scientific Information Retrieval) Database
  .SRB  Corel ClipArt ScrapBook
  .SRC  Sourcecode (various)
  .SRF  Sun Raster Graphic File
        Siebel Repository File (compiled objects)
  .SRI  Voice It Link Compressed Voice File [Free player]
  .SRM  Super Nintendo ROM Saved File (saved game)
  .SRP  QuickLink Script
  .SRPM  Redhat Linux RPM Source File
  .SRT  BSplayer Subtitle File
        SDR99 Speech Recognition Task Speech Recogniser Transcript
        Omron CX-Supervisor (Factory Automation)
  .SS   Splash Bitmap Graphic
        DrScheme Programming Environment File
        XShipWars Sound Scheme File
        Ribbons File  (protein analysis)
        Oberlin DRAGN Graph Algorithm
  .SSA  Subtitles
  .SSC  HP Library and Tape Tools Script
        SwordSearcher File
        Scrippy File (E-mail stationary)
  .SSD  SAS Database
        Snagit Studio Design File
  .SSF  Enable Spreadsheet File
  .SSH2  SSH Secure Shell Client
  .SSI  Installer/GD Software Setup Information
        SriSun  [XnView]
  .SSK  SwordSearcher File
        SmartSketch File (Use Hijaak to convert - SmartSketch became FutureSplash which became Macromedia's Flash)
  .SSL  Corel Flowchart Symbol Library File
  .SSM  RealPlay Standard Streming Metafile
  .SSP  SAS Transport Data
        Axialis Screensaver  [XnView]
  .SSS  Sudden Strike Saved Game
  .SST  Certificate Store
        Sea Surface Temperature File
  .SSX  ScreenShare Data File
        VersaPro Smart Store Document
  .SSY  ScreenShare Compressed Data File (compressed .SSX file)
  .ST   SMALLTALK Program File
        Scream Tracker Instrument Library
        Atari ST Disk Image
        NeoPaint Stamp File
  .ST4  SBIG CCD Camera ST-4  [XnView]
  .ST5  SBIG CCD Camera ST-5  [XnView]
  .ST6  SBIG CCD Camera ST-6  [XnView]
  .ST7  SBIG CCD Camera ST-7  [XnView]
  .ST8  SBIG CCD Camera ST-8  [XnView]
  .STA  Eudora File
        Statistica Spreadsheet
        Spinmaker Plus Stack
        Reflection Saved State
        Brazilian MSX Emulator - BrMSX Saved State
  .STB  Genus Stub Library
  .STD  Prosa State Transition Diagram Graphic
        SureThing CD Labeler Document File (Labels CDs, DVDs, Jewel Cases, etc.)
        LocoScript Standard Script File
  .STEALTH  Likely a text file (e.g., README.STEALTH)
  .STEP  AP203 Step File
  .STF  ShrinkToFit Compressed Archive File
        Setup Information
        Structured File
  .STG  PageKeeper Storage File
        MS ActiveSync (backup of data on mobile device)
        Statistica Graphics File
        Visual Pinball High Scores (and other data: vpreg.stg)
  .STK  Personal Stock Monitor File
  .STL  Certificate Trust List
        Macromedia Fireworks Style Library
        CAD Software Solid Modeling/Prototyping File
  .STM  Sound File
        Prosa State Transition Diagram Model
        Scream Tracker v2 Module
        SHTML File (HTML File Containing Server Side Directives)
        SDR99 Speech Recognition Task Time Segment Time Marked File
        PhotoStudio Stamp  [XnView]
  .STML  Sealed HTML File [Unsealer]
  .STN  STiNG File (Iterated Systems resolution-on-demand images)
  .STO  Genus Pascal Stub OBJ File
        Infinity Engine Game Storage File
  .STP  PageKeeper Packed Storage File
        DART Pro 98 System Settings
        AP203 Step File
  .STR  dBase Structure List
        DataPerfect Structure File
        Fifa 2002 Music File
        Statistica Report File
        Stream File (Playstation Discs)
        Music File
  .STS  MS C Project Status Info
        Scream Tracker Song
        Nimbus 7 SAMS Data File (status data)
  .STT  Automap Template
        SureThing CD Labeler User Template File
  .STU  Tarantella Enterprise 3 3270 Emulator Style File
        xyALGEBRA File
  .STV  sofTV.Author File (Streaming Video Web Authoring)
  .STW  SmartTerm Data File
        Statistica Workbook File
        Neopaint Stamp  [XnView]
  .STX  Simply Tax Form
        EditPlus Syntax File
        SmarText E-book
        SBIG CCD Camera ST-X  [XnView]
  .STY  Style Sheet (various)
        MS Interactive Music Control
        LaTeX2e Style
  .SUB  CloneCd Related File
        Divx Subtitles
        SubmitWolf File (search engine submission program)
  .SUD  Super Project Analyzer Data
  .SUI  Simple User Interface Toolkit Library
  .SUITE  Winstyles Theme (customizes the Windows Desktop)
  .SUL  GFA Ray-Trace  [XnView]
  .SUM  Summary (various)
  .SUMP  Easy Palette Gallery or Library
  .SUN  Sun Raster Graphic File  [XnView]
  .SUNIFF  Sun TAAC File  [XnView]
  .SUP  WordPerfect Supplemental Dictionary
        Super Porject Analyzer Project
  .SUR  Surveyor Document
  .SV$  AutoCAD Autosave File
  .SV1  Transport Tycoon Saved Game [TT Info]
  .SV4  RollerCoaster Tycoon Saved Game
  .SVB  Statistica Macro File
  .SVC  Statistica Macro File
  .SVD  Word Backup File [Buy Office XP at Shop.Microsoft]
  .SVF  WinSFV (Checks for damaged .rar files)
  .SVG  Word Backup File [Buy Office XP at Shop.Microsoft]
        Scalable Vector Graphics File
        Lode Runner Saved Game
  .SVI  Mimio Ink Files
        Red Faction Game File
  .SVL  Scramdisk VoLume (Win98 freeware also opened by DriveCrypt)
  .SVO  Statistica Macro File
        Transport Tycoon Custom World [TT Info]
  .SVP  WISCO Survey Power
        SwiftView Command File
  .SVQ  Roland Keyboard Midi Sequence
        InfoBind File Format  (encryption format used in Fuji SmartMedia cards to prevent copying)
  .SVS  Word Backup File [Buy Office XP at Shop.Microsoft]
        DART Pro 98 Spectral View Settings
  .SVX  Interchange File Format, 8SVX/16SV
        Amiga 8SVX Sound
        Statistica Macro File
  .SW   Audio File
        Raw Signed Word (16-bit) Data
        SmartWare Spreadsheet (requires login)
        EARS Component File (EARS = UK Liberal Democrats Election Agents Record System) [Filename starts with E]
  .SWA  Shockwave Audio File
        SATLOC FreeTrac (GPS Guidance and mapping)
  .SWB  PageMaker 7.0 ColorSync Component
        Super Win-EBook 98 File
        Sametime Whiteboard File
  .SWD  Storybook File (educational)
        Sabiston Textbook
  .SWF  Macromedia Flash Format  [Alternate]  [IrfanView]
        Microsoft Sidewinder (Force Feedback Joysticks) Profile Activator
  .SWFS  Dreamweaver File
  .SWG  Swag Reader Packet
  .SWI  Swish Data File (Swish makes Flash files)
  .SWK  Swapkeys Keyboard File
  .SWL  Macromedia Flash Format  [Alternate]
  .SWP  Sprint Backup File
        Swap File
        Spider Writer Project File
  .SWS  S-PLUS Workspace
        Swift Generator Instruction File
        SmartWidgets File
        Screen Writer Studio File
        VHDL Simili Sonata Project File
        Science Workshop File
  .SWS0  Screen Writer Studio File Backup
  .SWT  VB Setup Wizard Template File
        Macromedia Authoring Flash File
        Swift Generator Template File
        Space Watch Pro Data File
  .SXC  OpenOffice.org Spreadsheet File
  .SXD  OpenOffice.org Draw File
  .SXF  Secure eXchange Format File (Phocis Licensing Client)
  .SXG  OpenOffice.org Writer 6.0 Master Document
  .SXI  OpenOffice.org Presentation File
  .SXLS  Sealed Excel File [Unsealer]
  .SXM  OpenOffice.org Math File
  .SXP  OpenOffice.org Presentation File
  .SXW  OpenOffice.org Writer 6.0 Text File
        Staroffice Word Document
  .SY#  Darn! Backup Files
  .SY1  Ami Pro Smartpix Symbol Library
  .SY3  Harvard Symbol File (Harvard Graphics taken over by Serif)
  .SYD  Sysedit Backup File
  .SYL  SYLK Spreadsheet Format
  .SYM  Symbol Table (various)
        Borland C++ Precompiled Headers
  .SYN  Synonym File
        TextPad Syntax Definition
        SDSC Image Tool File
        Breakneck / N.I.C.E.2 Archive  [Dragon UnPACKer]
        Excessive Speed Archive  [Dragon UnPACKer]
        Synthetic Universe  [XnView]
  .SYNU  Synthetic Universe  [XnView]
  .SYS  System Configuration
        System Device Driver
  .SYW  Harvard Symbol Graphic (Harvard Graphics taken over by Serif)
        Yamaha SY-series Wave Files
  .SYX  SysEx MIDI File
  .SZ0  Binary File Format (used when uploading via a COM port)