Here is a summary of the most common graphics file formats:

Common Raster Graphics Formats
file extension MIME type proper name description
.bmp image/bmp Windows Bitmap Commonly used by Microsoft Windows programs, and the Windows operating system itself. Lossless compression can be specified, but some programs use only uncompressed files.
.fpx image/fpx ??? Flashpix (1.0.2) Uncompressed / lossy, 8-bit grayscale & 24-bit color. Provides multiple resolutions of each image.
.gif image/gif Graphics Interchange Format Used extensively on the web, but sometimes avoided due to patent issues. Supports animated images. Supports only 255 colors per frame, so requires lossy quantization for full-color photos; using multiple frames can improve color precision. Uses non-lossy, patented LZW compression. This patent expired in 2003.
.iff .ilbm ? Interchange file format / Interleave bitmap File format popular on the Amiga computer. ILBM is a subtype of the IFF fileformat, which can contain more as just pictures.
.jpeg
.jpg		 image/jpeg Joint Photographic Experts Group Used extensively for photos on the web. Uses lossy compression; the quality can vary greatly depending on the compression settings.
.mng video/x-mng Multiple-image Network Graphics Animation format using datastreams similar to those of PNG and JPEG, originally designed to replace the use of animated GIF on the web. Free of the patent associated with animated GIF.
.pbm ? Portable Bitmap Format A simple black and white graphics format. Unlike most graphics file formats, a PBM file is plain text and can be processed with text procesing tools. It is related to the PGM (grayscale) and PPM (color) graphics file formats.
.pcd image/jpcd ?? ImagePac Photo CD Proprietary Kodak format, lossy, 24-bit color.
.pgm ? Portable Graymap Format A simple gray scale graphics format. Unlike most graphics file formats, a PGM file is plain text and can be processed with text procesing tools. It is related to the PBM (black and white) and PPM (color) graphics file formats.
.png image/png Portable Network Graphics Non-lossy compressed bitmap image format, originally designed to replace the use of GIF on the web. Free of the patent, which expired in 2003, associated with GIF.
.ppm ? Portable Pixmap Format A simple color graphics format. Unlike most graphics file formats, a PGM file is plain text and can be processed with text procesing tools. It is related to the PBM (black and white) and PGM (grayscale) graphics file formats.
.psd application/x-photoshop Photoshop Document Standard Adobe format for Photoshop documents. Has many extra features such as image layering. Supported by very few programs other than Adobe Photoshop.
.psp ? Paint Shop Pro Document Standard Jasc format for Paint Shop Pro documents, similar to .psd for Photoshop. Supported by very few other programs.
.tiff, .tif image/tiff Tagged Image File Format Used extensively for traditional print graphics. Lossy and non-lossy compression available, but many programs only support a subset of available options.
.xcf ? eXperimental Computing Facility Native format for the GIMP. Has many extra features such as image layering. Used mostly in the GIMP, but also readable by ImageMagick.
.xpm image/x-xpm X-Pixmap Used almost exclusively on UNIX platforms with the X Window System. An ASCII format which uses no compression designed so that files are in C(++) syntax so images can be included in source code.
? ? OpenEXR A high dynamic range imaging file format, open sourced by Industrial Light and Magic.

Common Meta-File Formats (either Raster or Vector)
file extension MIME type proper name description
.eps image/eps ?? Encapsulated PostScript Used for a PostScript (.ps) output device.
.pct image/pct ?? Picture Default for pre-OSX Macintoshes (OSX default??)
Common Vector Graphics Formats
file extension MIME type proper name description
.ai application/illustrator Adobe Illustrator Document Vector format for Adobe Illustrator.
.cgm image/cgm Computer Graphics Metafile ISO Standard - It is used in the aviation industry. (CGM members)
.dxf image/vnd.dxf ASCII Drawing Interchange Standard ASCII text files used to store vector data for CAD programs.
.eps ? Encapsulated PostScript A PostScript file that describes a small vector graphic, as opposed to a whole page or set of pages.
.fh ? Macromedia Freehand Document Vector format for Macromedia Freehand.
.fla ? Flash Source File Shockwave Flash source file, only usable by Macromedia Flash authoring software.
.pdf application/pdf Portable Document Format A much simplified version of PostScript allowing for files containing multiple pages and links. Works with Adobe Acrobat Reader or Adobe eBook Reader.
.ps application/postscript PostScript Generic vector-based page description language, created and owned by Adobe. Postscript is a powerful stack-based programming language. Supported by many laser printers.
.svg image/svg+xml Scalable Vector Graphics An XML based vector graphics format, as defined by the World Wide Web Consortium for use in web browsers.
.swf application/x-shockwave-flash Flash Flash is a web page plug-in that displays vector based animations contained in SWF files. Several applications can create SWF files; these include the Flash authoring tool from Macromedia.
.wmf image/x-wmf Windows Metafile Stores vector graphics and raster graphics as a sequence of commands to be issued to the graphics layer of the Microsoft Windows operating system.