Here's a resource for you.  Some of the goods ARE dated now - the page has been hanging for so long - but Acadia, Mistress of Links, gathered together many fine resources here:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2635126

Years ago, R'osity updated servers and many of my favorite links no longer worked.  I gathered together what I could find and hung that list online.  Acadia's list is much more detailed.

Renderosity itself - and this long running forum - is an amazing resource for learning Poser.  And the people here who have helped me in the past is manifold.

PS: my rainbow MAT has fewer nodes ... I wonder if I should re-visit that thread.