I play the following regularly:
Game Name (Engine Name)
Team Fortress 2 (Source)
Killing Floor (UT 2005)
Call of Duty 5 (COD 4)
Left 4 Dead (Source)
Settings for all games:
1440x900
Models, Textures, Etc: High
Anti-Aliasing: 4x
Anistropic Filtering: 4x
As long as a I set my fans in OS X (via SMC Fan Control) to 5-6 thousand rpms my computer can run at this level and stick around 65 C.