I think Call of Duty 2 is out for the mac.
Another option is to use the dual OS method. It's a fact that more games are made for the Windows platform. With BootCamp (free), you can install a bona fide version of Windows (Vista or XP) on your intel mac. With Bootcamp you cannot run both OS X and Windows at the same time, you have to shutdown and reboot. (This might change in the near furture, like October, because the version of BootCamp in Leopard will have the ability to put one OS asleep and run the other).
Another way is to use Parallels Desktop and VMware. With this you can run windows and mac os x side by side (I don't know about the 3D performance in these virtual machines)
I would suggest go with BootCamp.
EA is releasing a few of its most popular titles on the Mac so you could wait for them to release it (Battlefield 2142, NFS: Carbon, Harry Potter, and C&C3)