We're pretty sure you've heard by now: Switching from incandescent lightbulbs to compact fluorescent lamps (CFLs) is a great way to save energy and money. But your environmental responsibility doesn't end there. CFL bulbs contain a small amount of mercury, a neurotoxin, so it's important to dispose of them properly. (To put the amount into perspective, consider that one CFL bulb contains between 2 and 5 milligrams of mercury, whereas the nation's coal-fired power plants spew out about 50 tons of mercury per year.) Some manufacturers have already implemented strategies to reduce mercury content in CFLs. While they're working on that, you can do your part by keeping CFLs out of landfills.
Don't throw CLFs in the trash. Some manufacturers, like Osram Sylvania, accept returned CFLs for recycling. Retailers, like IKEA, also have take-back programs. Find your nearest CFL recycling center at RecycleABulb.com, or consult the EPA's directory of recycling facilities. If a bulb breaks, the EPA recommends opening a window and leaving the room for at least 15 minutes. Keep children and pets away from the broken bulb, and follow these steps for safe clean up and removal.
Update: Home Depot now accepts used CFL bulbs for recycling.