Turn the lights on when you enter a room. Turn the lights off when you exit. It's a golden rule of energy savings, and it couldn't be simpler to follow—in theory. In practice, however, many people end up paying extra to the electricity company for at least some amount of unnecessary lighting. Here's the good news: You can trim that expense with a product like the Lutron Maestro. Leveraging motion-sensor technology, the switch can turn the lights on and off for you, automating your home lighting and saving you energy (and hassle) along the way. Available at Amazon; $29.