Most screen savers just waste power. Might as well just put your computer to sleep. But if you want to use a screen saver and you want to do something good for humanity then check out one of these:
fightaidsathome.scripps.edu – Join more than 300,000 other computing nodes and dedicate your computing power to finding new AIDS treatments
climateprediction.net – Improve climate prediction models with the University of Oxford
mersenne.org – Help George Woltman be the first to find a 10 million-digit prime
einstein.phys.uwm.edu – Test Einstein’s theory of gravitational waves

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