Treehugger featured a story today about a new efficiency calculator with a Halloween theme.

I hope they upgrade the calculator with additional areas for improvement, like wrapping the water heater and using an Energy Star fridge. As is, you can't really get a complete picture but it's a good start. What I like most about the calculator is that it estimates the savings of both dollars and pounds of carbon dioxide. I put in the numbers for what changes I've already made and the results are $750 and 10,000 pounds of CO2 saved! Try it out.