Adeona

Excerpts:
Adeona is the first Open Source system for tracking the location of your lost
or stolen laptop that does not rely on a proprietary, central service.
This means that you can install Adeona on your laptop and go — there's no
need to rely on a single third party.
What's more, Adeona addresses a critical privacy goal different from existing
commercial offerings. It is privacy-preserving.
This means that no one besides the owner (or an agent of the owner's choosing)
can use Adeona to track a laptop. Unlike other systems, users of Adeona
can rest assured that no one can abuse the system in order to track where
they use their laptop.


for more details click here
or

http://adeona.cs.washington.edu/