The setup guide for the XRay Raycer is quite good at my opinion.
No theory. Just explanation of how each adjustment option effect the handling. This is followed up by a guide on how to make the adjustment.
The "how-to" sections are of course made for the Raycer, but most can be adapted to many other cars.
Another good thing, the adjustment options are in order according to the order they should be adjusted.
It can be downloaded here.
(english, PDF - it's also on www.teamxray.com