Day 6 of the Steam Summer Sale, 2012. New games are put up for sale every day.
Company of Heroes for $2.49 (75% off)
Spec Ops: The Line for $33.49 (33% off)
LIMBO for $2.49 (75% off)
Wargame: European Escalation for $19.99 (50% off)
Stronghold 3: Gold for $13.59 (66% off)
Railworks 3 Train Simulator 2012 for $3.49 (90% off)
Call of Duty Black Ops for $19.99 (50% off)
Grand Theft auto IV for $4.99 (75% off)
Indie Bundle VI for $9.99 (75% off)
I recommend getting LIMBO and GTA IV. Call of Duty: Blacks Ops is also on sale for a nice price and a lot of people like it, but I've always been more of a Battlefield type of person (Bad Company 2 and Battlefield 3) so I can't personally vouch for it.