I usually do it when I want to ponder about something, usually depending on the mood. System for when I am angry and "Happy" playlist for when I am sad/upset. Gorillaz, Muse etc. Never really did it for the bass, I just listen to the lyrics.
Few songs that cheer me up:
http://www.youtube.com/watch?v=H8Qp38qT-xI
http://www.youtube.com/watch?v=hSFLJRBQpFo
Anger, Grr:
http://www.youtube.com/watch?v=1TteLSVxsCg
Disconnect and self destruct, one bullet a time.








