actaully, i didnt, but I wish i had !
http://preyproject.com/
install a little bit of code, it sits in the background and checks to see if your laptop or desktop or whatever has been stolen. If you say it has via the website, then when it gets connected to the internet the next time and sees that it has been stolen, then it snapshots the wifi node, does a screenshot of whatever they are doing at the time (facebook login, etc) and then even better takes a webcam (if built into your laptop) of the person actually doing it.
You get 3 free setups and I cant wait now till some toerag takes one of mine. Ive tested it so far and its got the location and the rest down to an art.
Sure the savvy thief might wipe it and re-install the OS but the number of people I have heard who bought a mac cheap but somehow dont "know" the admin password
I even have a few old laptops i am going to seed with this and leave on the train to find out who gets them.
Worse case scenario you get snapshots of yourself at midnight in your pants, LOL
its free and no sign up code, but I am pushing them for an aff prog!