Project BORG - BORG is a free network rendering system for RenderMan compliant renderers. It written in Java and comes with a graphical manager frontend. - http://oss.tautologix.com/project-borg/project/home/index.php
RManNotes - General information on writing shaders, in the RenderMan Shading Language, by using the two most commonly available RenderMan renderers. - http://www.accad.ohio-state.edu/~smay/RManNotes/rmannotes.html
Yahoo Groups: BMRT - User list for users seeking advice, receive critiques on work, critique and learn from the work of others, or share something great, including shaders. - http://groups.yahoo.com/group/bmrt/