I play eve on CrossOver on ubuntu hardy x64.  The premium graphics are
buggy, but the game itself works fine.  I couldn't deal with the cedega
thing anymore.

WoW also works under CrossOver or wine.  Had some occassional slight
graphics corruptions, but nothing horrible.

Everquest 1 and 2 work great under Wine.

Vendetta Online is a great descent-style space shooter MMO.  Has native
linux client.

DAOC, CoH/CoV, and Anarchy are also suppose to be flawless, but I haven't
tried them.

There are many development MMORPG's and your mileage will vary with them.

-- 
James McPhee
jmcphe@gmail.com