Solid engineering! Definitely needs a mobile app though.
Question that might be out of the scope of this HN post: what are some of the most obvious monetization models for this kind of services?
Edit: Last.fm doesn't scrobble music? Why?
Edit 2: After spending sometime on it, I'm loving it even more. I would suggest some sort of a community or rooms feature where I can discover music from a specific genre or style.