Oh I'm sure there's more than just four
But yeah I play and have since the beta - the game design forum I visit tends to attract alot of developers looking for people to look at game play and mechanics - so I've gotten to experience WoW, WoW:BC, LOTRO, GW, CoH, and CoV all in beta phases (hoping for Warhammer, Conan, or Fallen Earth next) but WoW is the only one I've stuck with as something to actual play with as a hobby.