Making your home more energy efficient saves you money and helps the environment. So get to work sealing those cracks and replacing those light bulbs! And don't forget your tax credits...
The US Energy Department's website for all efficiency questions. This is the place to start.
Compact Florescent Lighting
Questions about which kinds of CFLs to use in which lights, or how the wattage equivalents work? This site has it all.
Buy energy efficient products
A consumer's Guide to buying energy efficient products for the home
In your car
Inflate your tires
Cars use energy too, so here's a simple way to get better mileage.
More ways to help the environment
What is Carbon Offsetting?
This wikipedia page explains the concept of carbon offsetting.