Free MMOs I've played or been recommended
RPGSSilkroad Online (skill based system rather than race; you can learn every skill if you wanted to, obviously that'll take forever and not be very helpful)
Rappelz (best pet system I've seen so far.. if it keeps expanding it'll become like pokemon haha, and one of the first free MMORPGs to have awesome graphics - now it's pretty standard)
Maple Story (OMG I wasted my life playing this, slowest leveling system -__-. 2D platforming and keyboard bashing attack system, a great way to break a mouse is attempting to "party quest" as leader. You don't know what real KSing is until you've played Maple. It takes just one lightning mage to screw your day.)
Granado Espada (very unique system; you control a 3 player party and can expand your "family" so you can mix and match the 3 characters for different quests. to my understanding it's not free roaming, but the quests are instance based. so you go to an NPC in town.. and you can go on a quest, but you can't exactly walk to that quest area?)
Rising Force Online (one of the best free Sci-fi MMORPGs. who wants to ride a mech?)
Perfect World (fantasy with fairy wings and cat-girls for those who have that kinda fetish

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DanceAudition Online (It's like O2Jam from what I've hard.. i dont understand dance games, but a LOT of korean bands have gotten big from this)
Paid and/or coming soonI don't usually like paying for MMOs because I can't afford a pay every month thing.. that and how will you know you can play every month.. or get the most out of the $10-20 you pay to play?
Fury(I played this combat MMO in open beta. Basically it's an arena type PVP system where you win points which add to skills which you can buy. Fun, and you don't have to keep paying for it- just buy the game and play for free. Playability seemed kinda short, got boring after a while)
Eve Online(If there were one game I'd pay to play for is this giant space opera. The screenshots and review all rave about this space combat game, anyone wanna sponsor me?)
Aion(Delicious!! in development and will most likely be free to play)
PlaneShift(I was playing this in open beta like 2 years ago.. it's still stuck in Beta and when I played it the game had potential. It was extremely empty and the textures needed working on.. might be better now?)
Ragnarok Online 2(That's right fanboys and fangirls. RO is coming out in 3D soon.)
Stargate Worlds
(YES YES YES!! Stargate <3. It's under development, with a tentative end of year release. Can play as Goa'uld, Jaffa, Asgard and human *snore*. FPS style RPG.. will be definitely interesting. Fanboy <3)