Currently I have installed:
Guild Wars
Guild Wars 2
Borderlands
StarCraft
Mass Effect 2
After a little bit of tweaking, there's little to no performance difference from native windows and Wine. PlayOnLinux is also a pretty helpful tool for getting these games working well. Winetricks is a must. A little bit of patience and know how and you can pretty much get any game working well in Wine. Planetside has been one of the most challenging so far :P
Oh, the Wine database is pretty useful too. It's really helpful to find what windows settings and dependencies are needed for getting win apps to run nicely on Wine.
http://appdb.winehq.org/