The next major energy saving device I plan on purchasing for my home is the GreenSwitch. The idea behind the product is great: When your home is vacant, everything should be off! They also sell a thermostat that will revert to an "economy mode" when the GreenSwitch is activated.
The operating principle is simple: When you leave your house you press a switch that sends a signal to receiver units and cuts off all of their power. So if you have any lights, iron, TV, ceiling fan, etc. that you sometimes forget to turn off when you exit your home, you can install the GreenSwitch and it will automatically cut everything off when you leave.
From their website:
GreenSwitch eliminates the drain of unused electricity caused by unattended climate control, forgotten lights and "phantom power"—saving hundreds of dollars on electricity bills and greatly reducing environmental impact. GreenSwitch is easy to install as all components can be retrofitted into existing electrical systems. The GreenSwitch system is completely customizable, allowing the user to designate which electronics and appliances are affected as well as custom program their heating and cooling systems.
If you're already an energy saving fanatic, you may not need this product! But if you have a spouse/children that are unable to grasp the concept of light switches, this may be perfect for you.
The only issue I can see to widespread adoption of GreenSwitch in residential settings is the high initial costs, which I believe is somewhere around $1,000. However, depending on how wasteful your family currently is, this could still provide a nice payback. You can always figure out how you are using energy (and thus be able to get an accurate prediction of the GreenSwtich payback) by monitoring your home's energy.
Of course, another option to the GreenSwitch and an energy monitor is to replace your electrical panel with a product like the one by Computerized Electricity Systems; which monitors AND controls all outlets in your home!
Official GreenSwitch video: