It's Change a Light Day. Install some CFLs

A simple, inexpensive way to save money and energy at home is to replace incandescent lightbulbs with compact fluorescent lightbulbs. A good day to start your bulb-swapping if you haven't already is today, national Change a Light Day.

If every American household were to replace a single incandescent bulb with an Energy Star-qualified CFL, the energy saved would light more than three million homes for a year and reduce annual energy costs by $600 million, according to the U.S. Department of Energy.

Don't buy just any bulb—there are performance differences among CFLs, so our experts recommend using only Energy Star-qualified bulbs. And as we reported in this story about the myths and realities associated with these bulbs, today's Energy Star CFLs are much better than earlier versions, as manufacturers have addressed the problems of harsh light, flickering, and slow warm-up times. Even the mercury content has been significantly reduced.—Kimberly Janeway

Essential information: Proper recycling of CFLs is important. Learn about Home Depot's nationwide CFL-recycling program. And find out who invented the CFL. No, it wasn't Thomas Edison.