Sources

If you're looking for places to pull either file format information, or to verify stuff you've found, or to go that extra mile to track down variations, here's some similar endeavors and items.

List of Places Keeping Track of Formats

 * Forensics Wiki
 * http://archivematica.org/preservation
 * http://www.fileformat.info/
 * http://www.ace.net.nz/tech/TechFileFormat.html
 * http://wotsit.org/ - their download page is broken. need to ping webmaster about that.
 * Wikipedia: http://en.wikipedia.org/wiki/List_of_file_formats and http://en.wikipedia.org/wiki/List_of_file_formats_%28alphabetical%29
 * Also wikipedia:Template:Infobox file format (pages using this template)
 * http://unarchiver.c3.cx/formats
 * The PRONOM format registry.
 * http://wiki.multimedia.cx/
 * http://archive.org/download/file-format-encyclopedia/fileformat.zip/
 * http://www.digitalpreservation.gov/formats/fdd/descriptions.shtml
 * http://www.udfr.org/, see also http://gdfr.info/.
 * http://gitorious.org/re-lab Tools & specs from re-lab- graphics formats, and office formats
 * http://www-mmsp.ece.mcgill.ca/documents/AudioFormats/index.html - Documentation, details, specs, and samples for a handful of audio formats
 * http://wiki.xentax.com/index.php/Game_File_Format_Central This wiki is the home of the most game (archive) file format knowledge in the world.
 * http://rewiki.regengedanken.de has some more game related reverse engineering
 * http://mark0.net/soft-trid-e.html Home to TrID, which can identify a vast number of file formats using an updateable database
 * http://mark0.net/soft-trid-deflist.html Online searchable version of the TrID database file
 * http://file-extension.net/seeker/ Metasearch engine for file extensions - Find info about unknown file extensions or filetypes
 * http://www.vgmpf.com/Wiki/index.php?title=Main_Page - the Videogame Music Preservation Foundation Wiki has information on a number of formats used to play back videogame music
 * http://hackipedia.org/File%20formats/ - loads of info on various formats here
 * http://wiki.mobileread.com/wiki/E-book_formats - detailed information on eBook formats.
 * http://mediapedia.nla.gov.au/ - "The Mediapedia resource is intended to enable the identification of various physical media carrier types for assisting with collection planning, assessment, documentation, infrastructure and preservation planning for the content they hold. These could include media across various genres such as cine, video, photo, audio, data, paper carriers, microfilm, etc."
 * http://wiki.opf-labs.org/display/TR/Formats - Small list of formats with detailed descriptions of some known access/preservation problems.
 * CASPAR/DCC Representation Information Repository
 * The Software Ontology
 * KEEP Totem also covers software, hardware etc.
 * Dead Media Archives
 * The >4000 formats known to FI Tools, by extension, by MIME type
 * Python sourcecode for mimetypes module
 * /etc/mimetypes on *nix systems defines a number of file formats and mimetypes
 * http://www.iasa-web.org/tc04/key-digital-principles - Recommended Audio formats by Audiovisual Archives and Institutions
 * http://www.gpsbabel.org/capabilities.html - List of formats used by GPS devices
 * http://www.microsoft.com/openspecifications/en/us/programs/osp/office-file-formats/default.aspx Microsoft's Open Document Specifications
 * http://mamedev.org/source/src/lib/formats/index.html http://mamedev.org/source/src/mess/formats/index.html - format handlers for disk images, cassette images, and memory snapshots/quickloads in the MESS source code
 * http://minidisc.org alot of minidisc related info
 * http://cool.conservation-us.org/ Conservation Online
 * http://filext.com/ File Extensions with Mime types
 * http://en.wikipedia.org/wiki/List_of_file_formats_(alphabetical) Wikipedia list of file formats (alphabetical)
 * http://ist.uwaterloo.ca/~schepers/formats.html The C64 file formats list

Emulation

 * http://nonmess.retrogames.com/ - Emulator listing for various computer formats, including MESS and single-machine emulators.
 * The Emulation Framework is software developed by the international KEEP project, co-funded by the European Union's 7th Framework Programme.

Books

 * Compressed Image File Formats: JPEG, PNG, GIF, XBM, BMP by John Miano (1999)
 * Encyclopedia of Graphics File Formats: The Complete Reference on CD-ROM with Links to Internet Resources by James D. Murray and William VanRyper (1996) Copy Acquired! Text also online at FileFormat.Info and http://netghost.narod.ru/gff/graphics/book.htm . Information from the book on individual formats can be found from the FileFormat.Info's File Format Cloud at http://www.fileformat.info/format/cloud.htm or the format list at http://netghost.narod.ru/gff/graphics/formats.htm
 * The CD-ROM for the above book is located here.
 * Graphics File Formats by David C. Kay and John R. Levine (1994)
 * Graphics File Formats: Reference and Guide by C. Wayne Brown, Barry J. Shepherd (1994)
 * File Formats for Popular Personal Computer Software: A Programmer's Reference (Self-teaching Guides) by Jeff Walden (1986) Copy Acquired!
 * File Formats on the Internet: A Guide for PC Users by Allison B. Zhang (1996) Copy Acquired!
 * 3D Graphics File Formats: A Programmer's Reference by Keith Rule (1996)
 * More File Formats for Popular PC Software: A Programmer's Reference by Jeff Walden (1987) Copy Acquired!
 * Lotus File Formats for 1-2-3 Symphony & Jazz: File Structure Descriptions for Developers from Lotus, Inc. (1986)
 * Inside Windows File Formats by Tom Swan (Nov 1993)
 * Internet File Formats: Your Complete Resource for Sending, Receiving, and Using Internet Files by Tim Kientzle (Oct 15, 1995)
 * File Formats for Popular PC Software by Jeff Walden (Nov 1992)
 * PC File Formats and Conversions/Book and Disk (Developers Series) by Ralf Kussmann (Mar 1990)
 * Windows Undocumented File Formats; Working Inside 16- and 32- bit Windows by Pete Davis (Jan 23, 1997)
 * Graphics File Formats: The Complete Reference by John R. Levine and David C. Kay (May 1992)
 * Using Pcx Graphics Files: The Programmer's Definitive Guide to Pcx File Formats by Roger T. Stevens (Apr 1, 1996)
 * The File Formats Handbook by Gunter Born (Sep 1995)
 * X Window System File Formats and Application Conventions (X11R4) by The Open Group (Jul 17, 1991)
 * Guidelines on the Production and Preservation of Digital Audio Objects by IASA (2009)

Other Useful Materials and Services

 * http://www.nsrl.nist.gov/ National Software Reference Library (see also http://blogs.loc.gov/digitalpreservation/2012/05/life-saving-the-national-software-reference-library/)
 * http://www.openplanetsfoundation.org/software/fido Format Identification for Digital Objects
 * https://github.com/usnationalarchives/File-Analyzer File Analyzer
 * http://sk1project.org/modules.php?name=products&product=uniconvertor UniConvertor is a universal vector graphics translator. It is a command line tool which uses sK1 object model to convert one format to another
 * http://www.textfiles.com/programming/FORMATS/
 * http://wiki.opf-labs.org/display/SPR/Digital+Preservation+Tools Wiki list of digital preservation tool lists
 * http://wiki.opf-labs.org/display/REQ/Digital+Preservation+and+Data+Curation+Requirements+and+Solutions Digital Preservation and Data Curation Requirements and Solutions. Not classified by formats, but by datasets, issues and solutions.
 * http://fileformats.wordpress.com/ - The File Formats Blog
 * http://www.archive.org/details/cdbbsarchive - The Internet Archive has over 1,500 CD-ROMs loaded with shareware, and with that comes converters, documentation and other vital works related to file formats.
 * Crowd sourced Representation Information for Supporting Preservation (cRIsp)
 * National Software Reference Library
 * Linked Data URIs for MIME Types
 * http://darwinsys.com/file/ UNIX file(1) format guessing utility
 * http://www.filesignatures.net/ Online database of file signatures (magic numbers)
 * http://www.garykessler.net/library/file_sigs.html List of file signatures (magic numbers)
 * Data Formats from Paul Bourke Useful information on older formats. Categories include Geometric (e.g., 3-D), Audio, and Image.