Think your old windows might be leaking out your money in the form of heat? Worried that there are small creatures living in your walls? The Porter Cable Infrared Thermometer ($50) can help you find out. Measuring temperatures from -22º to 590º F, all you need to do is point it at the area you want to check — a built-in LED will shine on the wall, glowing blue for cold areas and red for warmer spots. As for what you do when you discover a gateway to the underworld inside your home? That's up to you.