A set of Matcaps for sculpting in blender. Most are new, but Ive included some older ones too. They are in Jpeg format. All of them have been made from photos I took, or from scratch in gimp.
Matcaps are used for quickly and cheaply shading a model so that you can get some amount of surface information (i.e. if there is an uneven surface that needs to be smoothed) very quickly in the viewport without the need to render. Its the same method used in zbrush and many other applications have adopted it.
Do I need more matcaps. Probably not. Do I want more matcaps. Hell yes.
My exact reaction as well. :)
As for what they are for, quick material previews while sculpting and/or spec reflections and diffuse color that more closely resembles the object you are sculpting.
Use GLSL shading and add a texture to the object's material mapped to "Normal" or "Reflection" (Can't remember which works/is better)
Reflection is the right option. CG Masters has a video guide, if you need it: http://goo.gl/lkm5Jl
Well im not rly good with sculpting what they are for?