www.gunzonline.com
My cousin sent me a link to this game. It is still in the beta stages... but it is very very fun.
You get your choice of guns, and a model. You can choose what server you want to play on, and then you join whichever room you want to play in.
You fight against people with your guns and a sword. It's a giant deathmatch, and very fun.
Very addicting.