Yesterday, I had a play with the intro code on http://learningwebgl.com/. I made this: (click image to run).
Pgup/pgdn turns out to be not the best keys to use in a browser for interacting with the thing. Some things were surprising:
Some of the recent criticisms of the most popular WebGL wrappers is that they either don't have a proper shader class, or that you are forced to use the same set of per-vertex attributes for every renderable - more like the last decade's computer graphics. So it looks like a good start will be: