So far I've gotten:
Warrior Within
The Two Thrones
Beyond Good and Evil
Brothers in Arms: Road to Hill 30
This totals to 20 dollars.
I've got Psychonauts and Braid in my shopping cart for 12 bucks, but I'm hesitating. I know I will eventually, though.
Team Fortress Classic is under 4 dollars right now, but I have no idea whether or not people still play it. Plus, you know, I've got TF2, which is pretty much perfect.
Dead Space is 11 dollars, but I'm sure I couldn't run it.