-inurl:(htm|html|php) intitle:"index of" +"last modified" +"parent directory" +description +size +(wma|mp3) "Madonna"
in del.icio.us
http://del.icio.us/tag/system:media:audio
http://del.icio.us/tag/system:filetype:mp3
http://del.icio.us/tag/system:filetype:mp3+mashups
http://del.icio.us/popular/system:filetype:mp3