Wow!
The Quake-Catcher Network lets you tap into the accelerometer in your laptop to detect and report earthquakes. (Note that not all laptops have accelerometers in them yet).
Apparently, the Quake Catcher Network detected the recent Los Angeles 5.4 earthquake in 7 seconds.
Brilliant!
Update: The only downloadable clients available now are for Macs. They're working hard on a Windows version.
