Holy shit! Lots of good stuff this week.
$6 Mirror's Edge, Prince of Persia, Mercenaries 2, and Shaun White Snowboarding, and MySims (stfu it's pretty fun if you like Animal Crossing) for PC!
The Day of Defeat: Source for $6 is also nice, but note that it's the European version. Would be careful about buying that, as it is a Steam game, and registering games from other regions is against the terms of use (and can get the games deactivated).
Also, Red Orchestra for $8 is a great game, if you're MAN ENOUGH FOR IT.