This exaile plugin turns the progress bar of the tracks into a bar which color depends on the tracks' mood.

exaile is a media player which incorporates many of the cool things from amarok (and other media players) like automatic fetching of album art, handling of large libraries, lyrics fetching, artist/album information via wikipedia, last.fm support, and optional ipod support (assuming you have python-gpod installed).

in addition, exaile also includes tabbed playlists (so you can have more than one playlist open at a time), blacklisting of tracks (so they don't get scanned into your library), downloading of guitar tablature from fretplay.com, and submitting played tracks on your ipod to last.fm.

exaile aims to be similar to amarok, but uses python and gtk+.