| skin | InstallShield Compiled Skin Data |
| skindex | Apple Mail Index Data |
| skl | Autodesk Maya Skeleton Works Data |
| sklib | Skatter Library Data |
| skm | SSEYO Koan Data |
| skn | Symbian OS Skin Data |
| skn | Windows Automotive Skin |
| skp | COREX Orthographic Transcription with Signal Linking Data |
| skp | SSEYO Koan Play Data |
| skpkmz | SketchUp Data |
| skr | Gaussian Scratch File |
| skr | PGP Private Keyring File |
| skr | ScriptIt Data |
| skt | SSEYO Koan Design |
| skt | SSEYO Koan Play Data |
| sku | TomTom for R-Link Map Update |
| sky | Adobe Acrobat Language Resource |
| skypechatstyle | Skype Chat Style Data |
| skypeemoticonset | Skype Emoticon Pack |
| sl | RenderMan Shader Source |
| sl | Sam Spade Startup Script |
| sl2 | Lowrance Sonar Log v2 File |
| sl2 | SQLite 2.0 Database |
| sl3 | SQLite 3 Database |
| slb | Multiframe Sections Library |
| slb | PSpice Symbols Library |
| slc | SLiCe Format Data |
| sld | Corel Paint Shop Pro Styled Line Data |
| sld | NEPLAN Graphic Export Data |
| sld | XnView Slideshow |
