Write this into a google search:
?intitle:index.of? mp3
You only need add the name of the song/artist/singer.
Example: ?intitle:index.of? mp3 nirvana
It works well with more popular bands/artists. Here's another example:
?intitle:index.of? mp3 jack johnson taylor
http://www.google.ca/search?num=100&hl=en&q=%3Fintitle%3Aindex.of%3F+mp3+jack+johnson+taylor&btnG=Search&meta=
the first link you get has the song and some other jack johnson songs. Try it out for yourself