Here's a link to a site with a rather lengthy list of free agents by position. Maybe someone on staff can sticky this for reference. Understand as time goes by many of these names will disappear as they re-sign with their current teams.
KFFL - 2012 NFL Free Agents
Edit: It has come to my attention that whoever composed this list may either have been drunk when they did it or didn't know what in the hell they were doing if they listed D'Brickashaw Ferguson as a 2012 UFA. The guy is signed through 2017. Therefore I would advise we double check some of these names to verify that they truly are UFA. One source for this is Spotrac.com which gives the complete contract and cap data on every active player. If a guy is UFA in 2012 this site will indicate it and it's a trusted source for this info.
The management of this site is truly sorry for any embarrassment these errors may cause.......well not really.