A while back someone asked about a free MMORPG, or just an RPG. Well 4Story just went into open Beta, and it's nice. Smooth graphics, solid questing system, easy grouping, and a Diablo style skill tree. It's your standard fantasy RPG format, but fun and easy to pick up. It is also much more refined than many others I have tried.
The download is pretty hefty for the client, but it has been a fun game so far. I haven't notice any of the items or abilities that you have to pay real money for yet like in many other free games. I am just at level 7, so I can't really do a full review.
http://global.4story.com/news/lastnews/list.asp
here's an entire list of some that look very nice. I haven't tried any other than 4Story, but if you do try some, let us know how they are. (there are a few race games, and others on here as well)