"the algorithm" has got to be a tough one though. You can't recommend very many bad fits for the user before they will stop using it, and unknown/lesser known songs are a huge gamble.

I badly want an algorithm that I can say, "Find me artists that sounds like <example-song> that have less than 1,000 subcribers (or whatever metric)" but I can understand why they don't do that (because there are very, very few people like me out there). It sucks.