Find a lost or stolen camera with stolencamerafinder
Interesting concept. I haven't tested it out yet, but it makes sense. You drop in a few pictures taken with the lost camera, the web app reads the serial number from the EXIF data, and scours the web for photos with the same serial number. With any luck, it will find photos the thief has taken with your missing camera.
Let me know if you've tried this out. What were your results?