GamersGate have just started their summer sale today, different genre each week with various bargains each day.
Week 1 is RPGs, some good deals there and quite a lot of games activate on steam. Just check on a game's page under DRM to see if Steamworks is listed. If there's anything you missed during steam's sales you may be able to grab it here.
SummerSale 2012 GamersGate - Buy and download games for PC now