As above, mmorpg is the place to keep abreast of the available games. The micro-payment model is becoming increasingly popular, both with punters and publishers, so expect to see more and more 'free' games coming our way.
Lotro is a very pretty and enjoyable game to play through once. It has practically no replay incentive at all. After all the repetitive grinding of most other MMO's I am really enjoying Tabula Rasa and it's frenetic combat and have done around 6 months in game.
If you fancy something a little different and a lot of fun, then City Of Heroes is cheap and good for a few months of play, but buy it through plaync to get the USA version of the game which is much better populated than the euro-game. It is looking a little long in the tooth now, but has really fun and interesting combat and an excellent mix of classes to encourage teaming etc.
If it has to be free, my mates are liking Exteel, a 3rd-person mech-style game and one or two of them are playing dungeon-runner which is a little like an mmo Diablo2 with a sense of humor.