It seems this is old Google tip but… To search files by their name and extensions like mp3 or other, just do:
intitle:index.of + “mp3″ + “gimme back my bullets”
To get results without *.htm or *.html files, perform:
intitle:index.of + “mp3″ + “gimme back my bullets” -htm -html
After that Google will give you a lot of file locations, sites that are hard to find normally.