‘Electric sheep’ is a screen-saver that generates fractal patterns and using distributed processing to create new ones. The results are often very beautiful and hypnotic fractal flames that can be worryingly addictive to just sit and watch.
You need to have a decent-speed always-on internet connection and a fair bit of patience for the first ‘sheep’ (ie. fractal flame) to download, but once you’re started you won’t regret it.
For a long time I never bothered having a screen-saver, I found them annoying and distracting, but now I’m happy to see the sheep pop-up and help me relax into thought.
They’ve just updated the software so now’s a great time to grab electric sheep for your computer:
There’s more info in the FAQ link, so check that out if you’ve got questions.