Steam has knocked 75% off the Serious Sam HD series, including a "double pack" with the first and second encounters for only $7.49. Direct2Drive has one of the better sales this weekend, cutting up to 75% off Bulletstorm, Crysis 2, Bad Company 2, Mass Effect 2, Medal of Honor and Shadow of Chernobyl. Meanwhile, you'll find 50% off Fallout 3 and Civilization IV courtesy of Microsft and Impulse.
Steam
Serious Sam HD titles 75% off
Hearts of Iron titles 70% off
SpaceChem $7.49 (50% off)
You Don't Know Jack $9.99 (50% off)
Impulse
Gothic titles 50% off
Supreme Commander Gold $9.99 (50% off)
Command and Conquer: Red Alert 3 Uprising $9.99 (50% off)
Sid Meier's Civilization IV: The Complete Edition $19.99 (50% off)
Rig 'n' Roll $17.49 (50% off)
Blood Bowl: Legendary Edition $19.99 (50% off)
GamersGate
1C titles 70% off
Revenge of the Titans $11.21 (25% off)
Direct2Drive
Various action titles 30% to 75% off
Games for Windows
Fallout 3 $9.99 (50% off)
EAStore
Crysis 2 $44.99 (25% off)
Good Old Games
Activision RPGs 30% off