Demon's Souls
Uncharted 2 (rent Uncharted 1 so you'll know who's who but definitely buy Uncharted 2)
Battlefield: Bad Company 2 (SKIP Modern Warfare 2)
Super Street Fighter IV
Valkyria Chronicles
LittleBigPlanet (I say wait for LBP2 but I bet you can find someone selling it around $10-$15 on...