Springs: James Siddall (of Super Plush Suspension) with the "lowdown" on springs.
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).