The head of the math department at my college actually taught one of these classes. He would assign two students each class period to take notes. He said that way, the rest of us could pay attention :) He would stand at the front and ramble about whatever came to mind, and scribble on an overhead transparency. He would start with a topic and take it wherever we asked: multiple dimensions, knot-tying, origami, computational geometry, ray-tracing. The course was called "3D Math" or something, so everything was relevant :) There were no tests, and we got to choose our own final projects. The notes and overheads were duplicated as study guides for the final, and the questions were taken right out of them. It was the most informative math class, if only because we were all doing our own thing and learning from each other.

I did a 3D extension of the Lyapunov fractal images that Mario Markus published in Scientific American in 1992. Markus's 2D: http://charles.vassallo.pagesperso-orange.fr/en/lyap_art/lya... and my 3D http://www.youtube.com/watch?v=-omN5ZM3Jho with a moving cross-section http://www.youtube.com/watch?v=ePRJfF3pwqg