Now that the film trilogy has resurrected interest in Middle-earth, if you're a fan of Tolkien's world, you need something to do while you're waiting for Peter Jackson to stop messing around with big apes and get on with The Hobbit.
Until then, a useful stop-gap could be The Lord of the Rings Online (formally Middle-earth Online), which has been freshly plucked from the grasp of VU Games and is currently being developed and published by Turbine, the company behind the Asheron's Call titles.