Wizards of the Coast/TSR:  These are the guys that brought us great games like AD&D, Revenloft for AD&D, Planescape for AD&D, Gamma World, and Alternity. 

Noble Knight Games: This is the best place to buy all your gaming products!  Tell them Giles sent ya!

Brutorz Bill's Alterniverse: This is an excellent site to find creatures both new and converted from other systems.  He even has Thunder Cats Alternity!!!  The ol' horse now posts information on two excellent campaigns set in his own D&D world.  Highly recommended.

Eric Noah's Dungeons and Dragons Third Edition News: If you are a fan of D&D and *still* have not seen this site, you are cheating yourself out of the best resource for 3E news on the net.  Check it out.

Unified Universe: This is a great D20 site from the guy that brought you Infinite Possibilities.  Check it out.  Good stuff.

Rolegamer: This is a great site for Mystara and Planescape information, the webmaster also creates logos for other sites.  Check it out.