My buddy Dan turned me on to this wild screensaver program called Electric Sheep, a screen capture of which is above. It's . . . well, let me just quote from the website, www.electricsheep.org:
"Electric Sheep is a free, open source screen saver run by thousands of people all over the world. It can be installed on any ordinary PC or Mac. When these computers 'sleep,' the screen saver comes on and the computers communicate with each other by the internet to share the work of creating morphing abstract animations known as 'sheep.' The result is a collective 'android dream,' an homage to Philip K. Dick's novel Do Androids Dream of Electric Sheep.
"Anyone watching one of these computers may vote for their favorite animations using the keyboard. The more popular sheep live longer and reproduce according to a genetic algorithm with mutation and cross-over. Hence the flock evolves to please its global audience. You can also design your own sheep and submit them to the gene pool."
I'm not expert enough to know if there is a danger of compromising your system integrity, but the site owners say no. And the results are really cool.