Check out this quick and easy calculator. It'll help you estimate how much money and carbon dioxide you'll save when you replace standard light bulbs with compact fluorescent light bulbs.
When you're done, share the calculator with your friends and find out who'll save more while helping the environment!
NOTE: Energy costs vary widely across the continental United States, from as little as $0.07/kWh in some rural areas, to more than $0.14/kWh. $0.10/kWh is roughly the national average; check your utility bill for your costs.