Wire the interior lighting on two circuits. Two circuits means that a single tripped breaker will not plunge you into darkness. Also, you can turn on half the lights during the day when you don't need as much artificial light, and both sets at night, when you need to do detailed work, or when...
A baby monitor in the garage with the receiver in your bedroom is a cheap alarm. They can pick up the sound of a baby sighing, so a break-in will sound like an explosion by comparison.
The design pressure stamped on a pressure vessel does not necessarily correspond to the operating temperature. It is often the maximum allowable temperature above which the vessel cannot safely contain the design pressure, and is based on the allowable stresses of the materials of construction...
I have used them as a poor man's stud finder. Place one on the end of a string, and swing back and forth along the wall. The magnet will stick to any drywall screws or nail heads under the mud.