The November 2004 issue of WIRED magazine comes with a CD of music by major artists. All of the songs are available under a Creative Commons license, and are freely distributable.
Using a BitTorrent-client like for example BitTornado, the CD is downloaded in a breeze and is very enjoyable to listen to – especially since it is a wide variety of musical styles and until now (I listened through around half the songs) there was none that I wouldn’t listen to a second time.
Direct link to the .torrent file.