The visualisation of music is a perfect vehicle for designers to graphically play - here's a classically themed collection which, whether you like classical music or not, are visually stunning.
http://www.projectthirtythree.com
http://symfantastique.blogspot.com
http://retrographica.blogspot.com
World Record Club (Australian) Covers - http://www.flickr.com/photos/23023719@N04/sets/72157603916589884/