Did a quick search and didn't see this posted anywhere. GamersGate has a lot of games with discounts:
http://www.gamersgate.com/giftguide?filter=
There are a lot of small, independent games it looks like. The one I plan on picking up is AI War for $13.95
They also have a 1C Advent calendar...
I didn't see this posted anywhere else, so I hope this isn't a repost...
I just got the new Game Informer magazine, and they had a Buy Two used Get one free coupons...one for games and one for DVDs.
Its the one with Crackdown on the front.