Theft prevention.
Short of having one of these...
[ame="http://www.youtube.com/watch?v=xGPVD2Fdh0k"]YouTube - Trunk Monkey 2[/ame]
...I like the idea of switching the coil negative wire. I was also thinking of armoring the ignition wires under the dash to prevent hot-wiring. I have also heard of anti-tilt mercury switches with alarms; however, it seems that someone leaning against the car sometimes sets them off. I will need to do further research.
Thanks for your input, guys.