From Takena Technologies:
Our CFL Savings Calculator will show you how much money you can save by switching from incandescent light bulbs to CFLs (compact fluorescent bulbs).
CFLs cost more to purchase, but they are up to four times more efficient than incandescent bulbs.
Use CFL Savings to quickly and easily calculate how much money you can save each year, and how quickly CFL bulbs can pay for themselves.
Features: Easy data entry. Calculates results based on bulb cost, expected life, energy use and cost. Use average electricity prices for your state (US), or enter the rate from your own utility bill. Answers to common questions and concerns about CFLs.