Having finally grabbed a hold of a graphics card that is capable of vertex programs, I thought I'd try to write a simple program that took advantage of modern hardware's programmable vertex processing. The first idea that came to mind: toon shading.

Using ARB_vertex_program I was able to write a simple program which used the dot product of each vertex's normal with the light as a lookup into a 1D ramp texture:

 

So given the Stanford Bunny, we get:

   

By drawing the silhouette we get some nice outlines:

 

And throwing in some stencil shadows we arrive at:

   

A scene that's a little more complex: