Juan José Torres is interested in procedural materials. He is describing the creation of several materials and offers them for download on his blog.
Juan José writes:
Little more than a year ago I began to experiment with Cycles shaders trying to build different procedural materials that could be easily reused in different projects and that would require no external textures. I've been posting those procedural materials in a section in my site called 'Surface Knowledge'. Very recently, I've published the fourth material in the series, procedural stippled finish, along with major revisions and updates for already existing materials. Node setups and blend files for all materials in the series can be found here.