With the new MacBook Pro's including built-in iSight cameras, I thought it would be useful to take an iSight snapshot of anyone trying to break into my laptop. This is done by tailing /var/log/asl.log for invalid login attempts (both at the login screen and screen saver). I have created an authsight program (1.5KB download) that provides a monitoring daemon which calls the camera after an invalid login attempt, and also includes a launchd manifest. An iSight command line tool named iSightCapture is also required.
It would not be too difficult to modify this tool to call home and even email photos should a laptop be stolen.
[robg adds: I haven't tested this one, but there are easy install/uninstall instructions in the package.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2006120918170984