Readymag - Readymag is a design toolkit that helps create immersive digital experiences without developers in days, not weeks.
FileProInfo - It's All About Files, Software, Online Tools - 100% Free
Publitas.com - Publitas helps you to drive more visitors to your online store by publishing catalogs online.
FileInfo.com - FileInfo is the central file extensions registry and contains a database of over 10,000 file types.
MadCap Flare - Documentation for Any Audience, Language or Format
File-Extensions.org - Large computer file extension library with detailed explanation of each file type with links to download free or associated software programs.