Bulletstorm is a hell of a lot of fun if you like being exactly how to play your linear cussfests.
The Worlds of Ultima games are free on GOG right now.
Indiefort 2 seems to have just launched.
A tower defense game with a twist, Unstoppable Gorg is 50% off at GamersGate. Well worth it for those who like tower defense games.
Driver San Francisco is $7.49 on Steam for the normal edition, or $8.74 for a few more tidbits (4 single player challenges and 3 multiplayer cars. Didn't even know it had multiplayer!). It's pretty darn good, at that price I can highly recommend it.
Origin is selling a bunch of titles at 5 $/£/€:
I don't see the EA sale prices except on special editions of some games up to 40% off. Is the $5 titles limited to Europe?
Try the store homepage, there should be a banner on the right side of the screen "great games for 5$"
Not really a "deal" but Gamersgate has acquired a couple Square Enix games they didn't have before and at reduced prices over other retailers. The Last Remnant probably the notable one, has a 15 dollar basic price, while it's been 30 or 40 dollars everywhere for what seems like forever. Might finally get dirt cheap if GG ever puts it on sale. Also have Front Mission Evolved, base price 12.99, usually 20-30 elsewhere. Both Steamworks.
I've attempted to start The Last Remnant a couple of times, but the battle system feels too automated, though not as bad as FF13. Admittedly, I haven't really given it a good try so it might get better. Definitely try the demo first.