Steam's midweek bonanza is a neat bisection of Call of Duty: World at War's retail price. Ordinarly $50, you can grab it for $24.99 until Thursday.
The franchise just dropped its third map pack - for the PS3 and Xbox 360 - but the first is still lurking out there for the PC version - and you get it for free, with your $25 purchase.
Call of Duty: World at War on Steam [Steam, thanks Ryan R.]