Got a solid list there man, and can probably sink 65 into getting all 3 of them, but a few others I can think of are
-Assassin's Creed 2 (now that they got rid of the DRM)
-Super Meat Boy
-Chime (it's five bucks, goes to charity, and is a combination of lumines and tetris, what's not to like there)
-Torchlight
-Left 4 Dead (1 or 2, 2 is bit more fun to play with the melee weapons, but 1 is a tad bit scarier, if only for the darker environments)
-In addition anything by valve as one other poster said, given that there the only company I can think of that has yet to release a actually bad game IMO.