gamestop.com and ebgames.com both have affiliate programs. I recently heard of 2 major gaming companies merging, but can't remember if it was these 2 or not. Chances are, they are the same company now.
I'm not an affiliate with either one of them.
http://www.gamestop.com/gs/affiliate.asp
http://www.ebgames.com/gs/sites/eb/affiliate.asp