Below is a list of useful links:
AR15.com - Lots of good information on AR-15s and other firearms.
AR-15 News - Great source for news about the AR-15 and other firearms in general.
M4Carbine.net - Lots of information about AR-15 based firearms.
Defending Firearms Rights:
Gun Owners of America - True defender of America's right to keep and bear arms.
Arizona Citizens Defense League - Grassroots gun rights organization in the state of Arizona.
Warlizard Tactical - Pistol, Carbine and Medical training in Tucson AZ.
M. D. Smiths Reloading Page - Excellent source for reloading on just about any caliber you can think of.
Civilian Gunfighter - Great blog about firearms training classes and general shooting to make oneself a better shooter.
Combat F.I.T. Krav Maga - Great Krav Maga classes in Tucson AZ. Highly recommended.