The Basics : James Siddall (of Super Plush Suspension) with the "lowdown" on suspension setup.
Lee Parks' Advanced Riding School (ARC) Suspension Setup: All though street oriented, these pages describe how to properly setup the suspension for any motorcycle. At the end is a handy "fill in the blanks" form that you can print out to help you arrive at the right settings. By Paul Thede (of Race Tech).
Jeff Bertrand's Rear Shock Tuning: In this short essay, Jeff (contributing editor and test rider for MCN) describes how he sets up the rear shock on a Honda ST1100. The basic tenets are valid for any bike.
Dirtbike Suspension Setup: Everything you ever wanted to know about dirtbike suspension. Excellent article of the inner workings of forks and shocks. By Bruce Tripplet (of Bruces's Suspension Service).
Motion Pro Fork Valve Upgrade for the WP: It may not be as "trick" as a professionally tuned suspension, but there is a lot of improvement that an owner can make with one of these kits.