DeDupester can load an mp3 library and eliminate duplicate files contained within one library. Future iterations of this project will support sorting and more library merging functionality. But thus far it has been very instrumental in increasing the size of my music collection via the sneakernet.  This was a group project I worked on for CS401

  More info:

   http://code.google.com/p/dedupester/wiki/DeDupester

you can grab it off the svn repository at the following location:

svn checkout http://dedupester.googlecode.com/svn/trunk/ dedupester-read-only

collin schroeder