The hottest thing in household energy savings is the compact fluorescent lightbulb (CFL), a funny-looking swirl that fits into standard sockets. CFLs cost three to five times as much as conventional incandescent bulbs yet use one-quarter the electricity and last several years longer. They are available virtually everywhere lightbulbs are sold. Most labels don't say "CFL" (GE calls its bulbs Energy Savers), and in some cases the telltale twist is enclosed in frosted glass. The wattage gives them away: many 7-watt CFLs are comparable to a regular 40-watt bulb, 26 watts is the typical CFL equivalent of 100 watts and so on. Or just look for the Energy Star label.
CFLs have come a long way since they were first introduced in the mid-'90s (they don't flicker as much when you turn them on, for one thing), but because each bulb still contains 5 mg of mercury, you're not supposed to toss them out with the regular trash, where they could end up in a landfill. So the bulbs are one more thing for you to sort in the recycling bin.
Light-emitting diodes, or LEDs (see item 4), don't have this problem, but they can require a bit of DIY rewiring. LEDs work great as accents and task lights, and you can also buy LED desk and floor lamps. But if you're just looking to put a green bulb in your favorite table lamp, CFL is the way to go.
Next Light Up Your City