Does using a dimmer switch with halogen lights save money on electricity?

I took some coursework to learn more about energy efficiency and although it was mostly about air conditioning the class really got my curiosity roused and so I bought a plug in wattmeter and started checking everything in the house. Yes, absolutely, dimmers reduce the load, even on auto transformers like low voltage lighting. I also found that turning down the volume on the TV and stereo reduced the wattage draw and that unplugging battery chargers did the same. The more I looked, the more I found. It sure is easy to waste something you can't see. I wonder how much energy your dimmer uses?