http://www.tuxgames.com/ http://www.icculus.org/lgfaq/gamelist.php http://www.happypenguin.org/ http://www.opengl.org/applications/linux/games/ At least it's more than OSX. Quick, how many different video cards are available for OSX?
http://www.linuxgames.com/ http://www.linux-gamers.net If you want first person shooters, most of the stuff made by id (Doom 3, Quake) would work with no problems. In general, there are many windows games which you can run through Wine. No guarantee that it'll work for all games, but it often does. Call of Duty, for example, will run through Wine. Some say it runs even better than on Windows XP.