I posted several months ago about how I was going to give DC Universe Online a go since it was free to play on the Sony PlayStation Network. I am not a huge MMO player. I fiddled with Dark Ages of Camelot and I have played (and now own) my share of MUDs and I did log about four years on and off on World of Warcraft. I have briefly tried a couple of the other free MMO's in the past, and they just never 'stuck' with me the way WoW did.
Plus a look at the new expansion, Garruk's Revenge
I surprisingly high amount of depth makes this trip to the moon worthwhile