Here's one I ran across involving car alarms.

If you don't have a home security alarm system, but have remote control on your key chain that has a car alarm panic button, at night keep in on ypur nightstand. If you hear any strange noises during the night, turn it on. Doesn't matter if the car is garaged or not, it will be heard.

I know this is deviating from the thread topic, but since car alarms was introduced, can't think of any better place to pass this on