Seeing how Humus provides the source code (isn't that the greatest thing?), it would be very cool to see what happens when different programers implement their take on the demos. A sort of "who can squeeze the most out of the demo" competition.
BTW, I always thought it would be really great if there were some people who would agree to implement the same basic demo for different hardware to show each side's story. For example, the notorious RTHDRIBL demo, but with framebuffer blending to show how the "same" thing would look and behave under such an implementation. This would allow us to see how different hardware approaches the same problems.