Is there any plugin for iTunes making it possible to tag the music with multiple tags (not ID3-tags or genre)? Just like last.fm does, e.g. "soft electronic african female-vocalist"? Genres are so totally unusable to use as a music categorizer.
I use iTunes a lot for syncing various iDevices and streaming music to the Airport Express, so I'm not really interested in an alternative app, even though I might be if it supports more or less everything iTunes does and have some more features, but also being compatible with and updating the iTunes library.
A big bonus would be if it's also allowing hierarchical tag structures.