Energy...

Does anyone in your house have an annoying tendency to stand in front of the fridge with the door open? Do your kids or your husband spend long minutes searching through the refrigerator or the freezer, letting the cold air out and wasting electricity?

Well, there's a solution. Many new refrigerators (like this Frigidaire) come with "door ajar" alams. If the door is open too long, the alarm sounds a reminder to shut it. This keeps the interior of the fridge from warming up and saves you a lot of energy that you would need to cool it back down again.

Of course, not every fridge has this feature, and no matter how bad your family member(s) may be, you don't need to buy a new fridge just to get an alarm.

If your current fridge doesn't have a door ajar alarm, you can also buy a simple magnetic door or window alarm and attach it to your fridge. These can be set to go off instantly or a few seconds after the door opens. 

If you're industrious, you can also build your own alarm circuit (method 1, method 2). 

By the way, this is also a great tool for dieters! Set the alarm to its shortest time possible -- or set it to go off as soon as the door is opened!