What's that old saying? Those who don't understand track profiles are condemned to reinvent them? This doesn't look all that new, but I only just found it: http://amarok.kde.org/wiki/Moodbar

There's even a "paper" linked from that page, claiming that "little research has been openly published" into this problem. Yes. That's because we -- mainly Toby -- completely solved it nine years ago. ;\)

Peter