There are two primary sites I would refer you to if you need to find other V-Ray Materials and Information. I have included links and descriptions of each below.
Flyingarchitecture.com has a wonderful collection of V-Ray for Rhino materials available for free to download. They also have a number of interesting tutorials and a wealth of 3D objects for use in Rhino/V-Ray.
Box Render Studio's V-Ray Materials
Box Render Studio's V-Ray Materials page is a collaborative effort of artists who use V-Ray for rendering. The primary materials on the site are for V-Ray for 3D Studio Max, but most materials can be easily adapted to V-Ray for Rhino (see Exercise 214 for instructions on how to do this). There are a number of tutorials on their site as well, but most are for 3D Studio Max or Maya.