FireFound is a free add-on for the Mozilla Firefox Web browser that helps you find your computer (or mobile phone, in the case of Mobile Firefox) if it is lost or stolen. Every time your computer's location changes, FireFound sends a secure message to a central server with its current location. You can then log into the server and see your computer's current location.
All of the location data is encrypted, so no one can find out where your computer is without your password.
If you lose your computer, you can tell FireFound to clear your personal data (saved passwords, browsing history, etc.) if anyone starts your browser before you can retrieve it.
If you sign up for FireFound Premium, your stored passwords would be encrypted and backed up to FireFound.com before being deleted from your computer. You could then restore this data from the FireFound Add-on's setings dialog. FireFound Premium is only $1 per month!
You can even run your own FireFound server; all of the code is open-source.
Note: All geolocation data that FireFound collects is approximate, and it should only be used as a guideline. If your computer has been stolen, do not try to retrieve it yourself - alert the police.