this is from the har-bal homepage. har-bal does automatic harmonic balancing of sounds u feed it. not free though.

the tutorial, however, is free and shows in detail how to set up a multiband compressor on your track, based on the waves linmb:

http://www.har-bal.com/mastering_process.php

http://hdqtrz.com/Files/Har-Bal_Mastering_Process.pdf

really nice i think!