Find Files With Google

If you’re looking for a particular kind of file (and yes, you can potentially abuse this), try searching for this on Google:

FILE_NAME_HERE intitle:"index.of" "parent directory" "size" "last modified" "description" [snd] (mp4|mp3|avi) -inurl:(jsp|php|html|aspx|htm|cf|shtml|lyrics|mp3s|mp3|index|null3d|listen77|indexofmp3) -gallery -intitle:"last modified"

Source and explanation