Torchlight II was my favorite game of 2012 and if you haven't sampled its brilliant loot-driven action, then GamersGate knocking 50% off its price (and 75% off its predecessor) should be tempting. GOG.com has a range of modern and old-school FPS games reduced to half price including games in the Unreal and Serious Sam series.
Amazon's Mayhem deals will continue until May 31 so check back daily for new reductions. Some of the deals that caught my eye were BioShock and BioShock 2 for $4.99 and Klei's excellent Mark of the Ninja cut down to just $3.75, that's 75% off its regular price. Jordan's already mentioned that Tomb Raider is going for just $13.60 on Green Man Gaming but there's also a weekend offer cutting the price off a number of soccer/football titles like FIFA 13 and Football Manager 2013.
Steam has a pair of games free to play this weekend; Josh has already let us know about Chivalry being free-to-play but the recently released Defiance is also as well this weekend and has got 30% off its price tag. As always friends if you find any great PC deals