Find which users take up the most disk space. This can of course be used to indentify any number of users so I picked 10 as an arbitrary number.
If you are already root (unlikely, but possible) you can remove the sudo -s part. Here's the command:
sudo -s du -sm /Users/* | sort -nr | head -n 10
sudo -s or it will give a few Permission denied errors before finally spitting out the results, and they may be incorrect. The directory structure should start with the /Users Directory and then it will recursively perform the operation. This may miss any folders outside of the normal user space, but there shouldn't normally be any user data there.
du process was using a lot of cpu, so it's best to do this while not running other cpu (or I suppose disk) intensive programs.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20130404072518701