There's an open source project developed by Washington University called Adeona that could help you track your stolen laptop. Here's the description about the project taken from the original site:
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.
Here's how it works (taken from the site again):
Adeona is designed to use the Open Source OpenDHT distributed storage service to store location updates sent by a small software client installed on an owner's laptop. The client continually monitors the current location of the laptop, gathering information (such as IP addresses and local network topology) that can be used to identify its current location. The client then uses strong cryptographic mechanisms to not only encrypt the location data, but also ensure that the ciphertexts stored within OpenDHT are anonymous and unlinkable. At the same time, it is easy for an owner to retrieve location information.
This application can be installed on Windows, Mac OS X, and also Linux. But you will need several tools installed for Linux, for example Cron for scheduling, traceroute, openSSL, and also iwconfig (optional). You will also need an Internet access to be able to track your laptop, since it will gather the data and send them to the server which will then track the location.