I play Counterstrike, DoD, (insert most steam games here), Warcraft III (DOTA and Use Map Settings maps), Civilization III Gold, and eve-online under wine. I play natively Battle for Wesnoth (my personal favorite), Glest, FreeCiv (a redone version of Civilization II for Linux), and Globulation is fun for a bit, too.
Forgot to add: If you haven't checked out Open Arena, it's basically a better version of Quake 3.