SETI@home is a scientific experiment that harnesses the power of hundreds of thousands of Internet-connected computers in the Search for Extraterrestrial Intelligence (SETI). You can participate by running a free program that downloads and analyzes radio telescope data. There's a small but captivating possibility that your computer will detect the faint murmur of a civilization beyond Earth.
Frequently Asked Questions (FAQ) about SETI@home.
Astrobiology at NASA: sometimes called exobiology, is the study of life outside the Earth.
Also visit the SETI Institute Online for more information.