
Not entirely the question you asked.... but website music is probably a number1 hate (though more so when its awful midi sounds)... if you want to use them, make it absolutely obvious where the 'turn off music' button is on the site so that site users have the option to turn it off, and quickly.
Most people are either listening to their own music... using a pc in a place where music is inappropriate (work, library) or cant hear them anyway.. and it is extremely irritating when the track changes as you flick from page to page.
Sorry to say but if i look at a site, no matter how interesting it is.. and there is music on it that i cannot turn off.. i leave and dont come back (hence i rarely ever look at myspace pages!).