Why wait for the users to come to your site? If you let me import my last.fm profile - and scrap all of my friend's profiles (they're linked from my profile) -

Why wait for the users to come to your site? If you let me import my last.fm profile - and scrap all of my friend's profiles (they're linked from my profile) - you should have all the data you need to start recommending music or generating some interesting charts. Overall, it's a great start. I think there's a lot of places you can go with it - definitely places to improve upon Last.FM and such.