Largest distributed astronomy project

With 1,516,000 participants in 224 countries (as of Dec 1999), SETI@home, launched on 17 May 1999 by the University of California at Berkeley, CA, USA, is a scientific experiment that harnesses the power of Internet-connected computers in the Search for Extraterrestrial Intelligence (SETI). Participants download and run a free program that downloads and analyzes radio telescope data. There's a small but captivating possibility that an someone's computer will detect the faint murmur of a civilization beyond Earth.