“Where is my Mac­Book” is a free ser­vice for find­ing a stolen Mac [ or any com­puter / cell­phone / etc ] started by a guy who had his stolen. That’s a crappy way to find inspi­ra­tion but there you go. From the site :

It works by set­ting your browsers home page to the url pro­vided once reg­is­tered, which when opened — in less then a sec­ond — records the IP address and redi­rects to your desired home page. In case of a stolen lap­top this infor­ma­tion can be given to local author­i­ties to prop­erly han­dle the situation.

The project is still in beta so if you want in, check out the offi­cial thread on MacThemes.

Offi­cial Site : [ clicky ] / Mac­Themes Thread : [ clicky ]