I think there’s a huge potential for improvement by applying this principle towards general energy use. Right now consumers usually think of their electrical outlets as a sort of unlimited fountain of electricity. If everyone had some sort of digital meter in their house in plain view (not like those ones in the back you never look at) that displayed how much electricity was in use and how much it was costing them (both in $/hr and their total bill so far), then people would be a lot more concious of turning their things off. The instant feedback they’d back would also provide info on how best to save electricity, e.g. which appliances use the most. Out of sight, out of mind. The meter could also display the amount of C02 they’ve caused to be emitted. Everyone blames the big energy companies, but the demand side of the equation is just as important as the supply.
(note: they do already have a handy gadget called a Kill-A-Watt that plugs into an outlet and tells you how much power a given appliance is using up)