I just found about these recently: www.earvana.com
Compensated nut, instead of just the saddle.
Haven't tried them yet but I am going to. Others I have talked to bought one to try, then bought them for every guitar they owned. Seems like a good idea.
Click on the "Technology" tab to see the pitch variations. Different than Buzz Feiten, the Earvana looks to work on every string, all the way up the neck.