EQ MP3
In case you haven't stopped by the EQLive! site recently, there is an ingame MP3 Player currently being evaluated on the Test server. This player will allow you to play any EQ music or your own MP3's while playing EQ and the music doesn't stop when you zone.
For some screen shots and info on using it if you pop into the Test server, use this link to the News article on the EQLive site.