Mabinogi - Fantasy Life
Here is a great game to consider in the Free MMO category. Mabinogi has a surprisingly relaxed atmosphere for an MMO. There is plenty of depth for hardcore gamers, an over arching story line, tons of skills to improve, and a seemingly endless number of quests to choose from. This game has an unusually high appeal to a more casual style of game play with a very high number of non-combat quests and odd jobs to take a look into.
Check it out and let me know what you think.