Data Formats
OpenStandards.net - http://www.openstandards.net
A not-for-profit organization created to connect people to open standards and the bodies that build and foster their growth, integrating the various resources within the IT industry committed to increasing the synergy of international IT collaboration.
Wotsit.org - http://www.wotsit.org/
Contains information on hundreds of different file types, data types, hardware interface details and all sorts of other useful programming information; algorithms, source code, specifications.