For Myself as a present Multiplayer: Eve Online
For S&G: Second Life
For outright fun: the old classics like Doom, Doom 2, Duke Nukem, Load Runner...
FEAR i kept getting fragged on >.<.
WoW has... torn apart friendships, its the devils work in a more built up form than PC's themselves reach alone!
Othewise, much SL time and EVE... both are a bit wonky, and Linden Labs is outright boned if they ever hope to introduce Havok2... but eh, SL pays for EVE, ive no complaints.