Free to Play

Awesome, thanks for all the ideas. now i have more ways to keep my broke ass entertained.

Battle of the Immortal. Kinda new, currently playing it with friends, who are like the top people in the Western server. Easy to play, but hard to learn. So goodluck

MapleStory, Shin Megami Tensei: Imagine Online.
Grand Fantasia, Neo Steam.
All very good games that are free.

ooooh yeah I know that game. If your into web-based real time simulations then this is a good office game. Office game why? coz it can take up to 2 days to finish a building or even more. I played it for a month only.

Nexon
Ogplanet

are a couple of sites with free online games.

Ragnarok Online is a great classical point and click MMO this is literally GRIND TO THE CORE. You dont need to party up at all, and if your that desperate to lvl up quickly bots are available.

Steam by Valve is a great portal for different games. it is free to download but you have to purchase the game. I know your looking for free games but if your willing to spend at most $20 then steam won't disappoint. I'm currently playing Torchlight and if you love diablo 2 you can feel the resemblance (not saying that its a rip-off)