Understanding energy usage is becoming more and more important for consumers. Get the information you need! I user a Kill A Watt energy monitor. Plug it into an outlet, and plug in an appliance to it, and it will show you the energy usage on its LCD screen.
This has been helpful for me to setup a few uninterruptible power supplies, as well as learn about how much energy our computers use. Our computers use between 1-2 amps of power, which is a lot. I'd love to drop that down as much as possible.
How to save electricity
Check out Green Computing Info for more about computer energy consumption.