If you work with Django like I do, you have a separate installation or Subversion check-out of Django for each of your projects. Currently each one of them eats 22 MB of disk space.
This utility hard-links all identical files between copies of Django. They can even be different versions or svn revisions, and you'll still be able to free a good amount of disk space.
Run this every now and then if you update installed copies of Django or add new ones.
This utility is available also here.