Ever since I got my 360 over a year ago I've been periodically re-buying games I already owned on Steam and PS3 with no intent of trading the old copies in. It started off with multiplayer games which are easily justifiable since I could then play with my friends who didn't own the game elsewhere. But then I started buying a few single player games, mainly due to sales on XBLA or Steam. So far my list consists of Super Meat Boy, Bastion, Mirrors Edge, Modern Warfare 2, Bioshock 2, Street Fighter IV along with a few others. Maybe I've been bamboozled by low low prices into buying something twice, but I don't feel too guilty about it.
So my question to you all is; what games have you bought more than once and why?