We've changed almost all our light bulbsin our house, office and barn to compact fluorescent lightbulbs (CFL's) that use only about 7-13 watts, rather than incandescents that use 60 or more watts.  The compact fluorescents not only use far less energy, but they last many times longer than incadescent bulbs.  Converting just one conventional light bulb to a compact fluorescent bulb can save you up to $30 or more in electric costs over its lifetime. 

CFL's are good for the environment - one CFL will prevent more than 110 lbs. of coal from being burned, and reduce greenhouse gas emissions by 450 lbs. 

I'm not a big fan of Wal-Mart, but it is requiring that thier CFL suppliers limit the mercury in these bulbs to less than the 5mg allowed by law. 

And, yes, because of the mercury, these bulbs need to be taken to the county's Household Hazardous Waste (HHW), rather than being thrown out in the garbage or recycled.  For burned-out CFL light bulbs, we hang a bag on the wall and put them in until we have enough to justify the stop at HHW, which isn't very often, since these bulbs last such a long time . We willingly stop by HHW on our way to town, whenever we have a material that can't go into our compost or into the landfill.

Please visit these links for more information on CFL's
American Council for an Energy-Efficient Economy
General Electric's info about compact fluorescent light bulbs

CfL's are commonly available now at Home Depot, Lowe's Target, Wal-Mart and other stores.  The big chains have made a commitment to making these bulbs available at low prices, to encourage everyone in America to switch to these energy-efficient bulbs. If we all switch, then, as a country, we will have taken a big step to reduced energy usage.