What I have been doing lately to build my library up is just typing into google what I'm looking for and then blender node set up or blender material setup etc. And then opening the images page, which has a lot of screen shots that people have people have posted with different variations of the material. Then build the setup myself which I find better than linking from someone else's source that I d/loaded. As I can see what each node does as I plug it in and how it effects the model as I build it up to the desired result. If I like what I have done then save it out as a blend file.

Incantrix