It would be awesome if they did something like the LoTR:O /music system. Not only could you play "live" and have other aroudn you hear it, but you coudl also write your own songs outside the game or create your own .ABC files and auto play them in game.

Something like this woudl be more likely to be implemted in game over say something like Gath suggested where it would steam what ever MP3 you had tied to your song for your party.