The Quake Catcher Network (QCN) is a research project that uses Internet-connected computers to do research, education, and outreach in seismology. You can participate by downloading and running a free program on your computer. Currently only certain Mac (OS X) PPC and Intel laptops are supported -- recent ones which have a built-in accelerometer. You can also buy an external USB accelerometer. QCN is based at the Stanford University School of Earth Sciences.