I don't want a multiplayer version of CHRONO TRIGGER (not even another multiplayer game set in the same world/storyline) but a game that looks and plays similar to it? Yup!! sure that would be amazing~
Other than that I agree with @retro-room list, especially any fighting game (there must be a way to play them online with emulators now right?)
Someone mentioned Bomberman... I'm surprised no one made a an online multiplayer game of it yet.