The term "shader" is a touch overloaded. On this page I'm generally referring to vertex and pixel shaders, mostly pixel shaders. I'm not an expert by any stretch of the definition, and my graphics work is far from ostentatious, but I do think I have a solid understanding of the graphics pipeline and physics; you might call me a hobbyist. I've done a couple of projects using GLSL and RenderMan, I've also played with HLSL.
The examples I'm presenting here are a mixture of personal, class, and professional projects. I'm also including some really basic examples just incase someone happens to stumbles upon this page in search of help or examples. I'm obviously not going to brag about a 2 line shader, but someone may find it useful in the future.
My experience with RenderMan is very limited. The shaders I made were for a graphics class I took. I remember that I had the flu while I was coding these up, good times. Since then I haven't really found a reason to revisit it, however the application of RenderMan shaders into my day-to-day work is limited at best. Regardless I still enjoyed doing these shaders, even if they are very simple.
The first shader is a very simple 'turn the lights on' effect. This might even be right from a text book, I don't remember.
This second shader was taken right out of the RenderMan Companion p.345. I did change it, but I don't remember how. I was sick after all. :)
This third shader was basically the same as the checkers on except we have circles and use the smoothstep function.
The fouth shader is the same as the third, except without the smoothstep.
I like the fifth shader. It's a very simple effect that simply causes the checkerboard to appear on the specular highlights rather than over the whole surface of the sphere; a cool like trick.
The sixth, and final, shader uses the classic bunny. The interesting effect here is that the bunny is actually shaded using a 3D shader. Basically, you can imagine that we started with a cube of yellow stuff which had red marbles in it, then we carved out the bunny. Personally I really just enjoy all the different ways that a shader can work.