I have to admit, this post might resolve an ongoing turn-off-the-lights/why-can't-I-leave-them-on-dimmed debate that has been ongoing in my household because dimmer switches DO indeed save electricity. If you have the newer dimmer switches, they now include a "Triac Switch" which cuts the flow of energy to the light. It causes a constant flicker which the human eye cannot register, cutting down on the actual electricity used to power the light. The best news is that if you use the dimmer switch at about 50% you will save money on your electric bill in the long run!
If you don't have dimmer switches currently and are looking to install them, you can find an easy seven step install how-to here.
Image: Micki Howl