Sometimes I need to find all of the duplicate files in a directory tree. I have this issue all of the time when I move my music collection. Here is a nifty script to sort these things out:

#!/bin/bash find -not -empty -type f -printf "%s\n" | sort -rn | uniq -d | xargs -I{} -n1 find -type f -size {}c -print0 | xargs -0 md5sum | sort | uniq -w32 -D --all-repeated=separate