There's a handful of game sales going on this week, the first of which is occurring over on the PlayStation Network for Ubisoft titles. Included in that sale are co-op games Scott Pilgrim vs. The World and Outland. PlayStation Plus members can get those games for 50% off - or $4.89. Everyone else can get it for 30% off - or $6.99. Scott Pilgrim features 4 player local co-op while Outland features two player online co-op.
If PlayStation isn't your thing, the Xbox is having a sale as well. The classic co-op game Castle Crashers is 50% off this week making it just 600 
. It features four player local and/or online co-op play with combo co-op support.
All these sales end on the 21st. of May.
Source: Blog.us.playstation.com