Prey is a lightweight application that will help you track and find your laptop if it ever gets stolen. It works in all operating systems and not only is it Open Source but also completely free.
Prey helps you locate your missing laptop by sending timed reports with a bunch of information of its whereabouts. This includes the general status of the computer, a list of running programs and active connections, fully-detailed network and wifi information, a screenshot of the running desktop and — in case your laptop has an integrated webcam — a picture of the thief.