Teach Your Computer To Get Smart.  Just see this easy tutorial to see how.  Also, if you have a lot of peripherals or audio/video equipment, plug as many as you can into one power strip and turn them all off at once.  You'll save hundreds more over the years because you'll avoid the "vampire mode" that most electronics enter when turned off, still sucking juice.

Conserve Hot Water.  Showers are a big part of both your energy bill and your water bill.  A household that uses a low-flow showerhead for 2 showers per day will save about $750 over five years.  Another idea is to just take fewer baths and shorter showers.

Do A Home Energy Audit.  Call your local power company and find out how to get one.  If you're the self-reliant type, you can try visiting EnergyGuide's Do-It-Yourself Energy Audit.

Use A High-Rebate Gas Card.  Some cards will pay you a 5% rebate on all your gas purchases.  This site has a Rewards Credit Card Scorecard that can help you pick the best card for your particular situation.