A number of titles are on sale right now on Steam, including a pretty amazing deal on the enormous THQ complete pack. Normally it's a great deal, right now it's a further 50% off, meaning that for $49.99 you get:

Company of Heroes
Company of Heroes: Opposing Fronts
Company of Heroes: Tales of Valor
Dawn of War II
Dawn of War: Gold Edition
Dawn of War: Dark Crusade
Dawn of War: Soulstorm

FrontLines: Fuel of War
Full Spectrum Warrior
Full Spectrum Warrior: Ten Hammers
Juiced 2: Hot Import Nights
Red Faction
Red Faction Guerilla
Red Faction II
S.T.A.L.K.E.R.:Shadow of Chernobyl
Saints Row 2
Titan Quest
Titan Quest - Immortal Throne

The sale will run over the long weekend.