MoodAmp is an MP3 music collection program with a difference. Quote: ‘Using adaptive learning techniques MoodAmp will manage huge mp3 collections easily and always plays music that suits your mood.’
The program scans your MP3 files, makes guesses as to the music types and starts playing stuff. You rate songs as you go, and MoodAmp learns what music goes with your different moods. Very much a work in progress, but fascinating nonetheless.