[Hampshire] Worthwhile screensaver

Hi all

Does anyone have any good recommendations for a "worthwhile"
screensaver?There are obviously thousands out there that either blank the
screen, play a video, draw a pretty picture or do something allegedly
amusing.

I'd quite like to have my spare clock cycles do something more useful -
though I'm not really interested in SETI. Anybody know of any good ones
that might do something interesting without guzzling my bandwidth?

Any ideas welcome, but as I say I'm not interested in cartoons or just
playing videos / slideshows etc.

Cheers
Rob