Tried
www.spotify.com yet? It's insane, virtually any music streamed for free, if you can stand some rare ads. The app is very responsive too - it's like if you had all the music in the world on your own hd. They have an ad-free service for ten $ per month or so, haven't tried that yet. I think this will turn out to be the killer app that will make music trading sane again. There will be little reason for pirating now, or for buying an album ever more for that matter. It's all already there - at least as long as you're on a computer. Very interesting.