these are all great ideas!

i second the notion for a wiki defining nodes.  i've been the the CastlePoser tutorials several times, and i still have no clue why Bias (x, y > 0.5) makes x = black into a grey, but Bias(x, y < 0.5) leaves x = black and x = white untransformed.  what equation does Bias actually apply mathematically?  and Gain? 

and that doesn't even touch on the black boxes of things like "skin," "velvet," etc.  i don't touch those any more, but lots of people do, yet there seems to be no clear understanding of how they transform their properties.  there are a lot of nodes with internal functions that would be easier to use if how they operated were actually available.

i think a series of tutorials on making different types of materials would be very different and also beneficial.  personally, though, i'd love having an accompanying script for each tutorial.  now that i'm into Matmatic, it's much easier to keep track of what someone else is doing (or even what i'm doing).  the structure and notes just work wonders.  considering something "wear" or "grain" is easier than following connections to from a group of 4 or so nodes to find out they're affecting color, reflection, specular, bump and displacement. translating nodes is a lot harder than translating code written in English, imho.