Tastebuds.fm did match based on music similarities, last time I checked. Although it was a bit shallow as it only matched based on number of artists shared. I t

Tastebuds.fm did match based on music similarities, last time I checked. Although it was a bit shallow as it only matched based on number of artists shared. I think better matching would also take diversity of tastes into account and how much importance you place on certain artists. It does have a feature to tag 6? artists as favorites, but that's it.