Sometimes life is just too hard. Relationships can be tricky, retail help can be downright unhelpful. And then somebody swipes your laptop. You really know you're going to have a bad day now.
VigiMac is a tool that, while it can't prevent your computer from being taken, may well help you to recover it. Once you install this app on your Mac, it phones home on a regular basis: every three minutes it contacts VigiMac's server. When it's reporting from your home or work location, nobody really cares, but once it's gone missing, things change. Now once somebody goes online with it, it will send back its IP address and you and the authorities have something to go in in terms of trying to track your property down.
VigiMac is a free Mac application. You can install it and use it to track one or two machines, or with a donation you can watch additional computers. It runs under OS X on systems using Tiger (10.4) or later.