I don't know why people still bother to make posts saying, help me find a great, free mmorpg. Pretty much what you see on this forum, or any forum discussing free mmo's give the same responses.
Most peopele end up saying Silkroad Online (grind 1000+ monsters for a quest, to end up grinding for more, while the GM's don't give a damn about bots), Maple Story (there is no end to the grind, but it's very flat, and mindless, and can be fun if you got the money and friends in the game), FlyFF (flyyyyyyy!), and so forth.
http://www.gamengame.com/en/ is somewhere that has a lot of games you can try out if you really want.
If you don't mind paying for a game, but not have to worry about monthly fees, Guild Wars is fun. But the thing is, I don't think the PvE is fun going through more than once, and once you're done, there's only so much chest runs you can do before you snap. The PvP is fun, but you pretty much need a lot of skills unlocked from all three games to get the full experience.
Jam it back in, in the dark.