The game of the weekend on GamersGate is Space Siege, where they have the action/RPG from Gas Powered Games for $4.99, which is 75% off. Impulse is now offering $4.00 off preorders of Stalin vs Martians, the RTS game to be released next week. Steam's Weekend Deal is 66% off The Orange Box, so this bundle of Half-Life 2, Portal, Team Fortress 2, and the two episodic Half-Life 2 expansions is $9.99, a $20.00 savings off the regular cost of TOB, and almost $75.00 off the individual prices of those games. The GoGamer 48 Hour Madness Page has a large number of sale offerings, though you may need to hurry, as the date indicates they've been listed there for well over 48 hours already.