Auto playlist generation based on similar tracks.

The only thing that's holding me back from Songbird is the lack of auto playlist generation based on similar tracks to one or more you select. Refer MusicIP Mixer or Winamp's playlist generator. One based on Last.fm recs selected from your own library would be ideal. This sort of feature seems to be much more common in Linux music players, e.g. Exaile does it really well.

I'm not talking about 'smart' playlist, which are still dependent on user specified criteria like 'tracks where artist name = x'. I mean a system which automatically makes a playlist of stylistically or acoustically similar tracks to one or more selected 'seed' tracks.

This would be a great plug-in, or whatever.