I have heard that if you have a light connected to a dimmer switch, turning the dimmer switch down doesn't reduce the power consumption -- it just converts the excess power to waste heat.
This makes as much sense as anything about the mystical forces in the wires does; a dimmer switch is an adjustable resistor, so it reduces the power available to the bulb by keeping the load constant.
On the other claw, I'm rolling poorly on my Google Fu dice; I can't find any references to confirm this, that explicitly state that turning down a dimmer switch doesn't save power in terms clear even to laymen with less grasp of the galvanic arts than mine.
And, devoted readers and honored friends -- if you don't have the Mojo, please refrain from offering responses of the "It seems to me..." and "What I think..." natures. I'm not looking for opinions; this is a field subject to rigorous measurement and mathematical analysis, and I want the facts from Those What Know Their Shit.