Ultima Online: Renaissance

This is the third edition of the Ultima Online series, with improvements including better graphics and the new dark facet, Felucca, the much more evil version of the light facet, Trammel. It still costs about $10.00 a month to play. Players can create characters and send them into the World of Brittania where they develop their skills and basically do whatever the heck they want. Of course, there's no guarantee that doing whatever you want won't get you beheaded, but that's fun too.