Not sure if it's been mention before, but I've always been amazed at the scope and detail of the sci-fi MMORPG
Anarchy Online.
It has one of the biggest game worlds I've ever seen, a super in-depth background plot, and millions of different futuristic items, from synthetic chocolate cake (which you can use to beat people to death with... slowly) to hover cars which you can fly around in.
Although it's not as RP-centered as PS, there's still a lot of RPers, and there's bars and clubs in almost every city, as well as an on-going story hosted by the GMs.
There's like, 13 professions, each one with unique abilities (Adventurers can morph into animals, Agents can disguise themselves as other professions, Metaphysicists can summon a horde of weird-ass minions, Engineers can build robots and craft stuff, etc.) And they have randomly-generated, instanced 'missions' where you run around the world following NPCs or recovering items without worrying about kill-stealing...
If I was gonna pay for an MMORPG, it'd be AO.
Oh yeah, and I'm pretty sure the original game is free forever, but if you want to use any of the 4 expansions you're going to have to subscribe.