I think the increasing prevalence of USB-powered devices will lead to exactly the sort of universal wall warts that you're talking about. You can already get stuff like this thing. Eventually, this will only get better.

The "resting" power consumption of our house is maybe 300W, which seems way too high, but I've been focusing my efforts on getting down the costs when we're home and things are on, which has led me down the (expensive) path of LED lighting. I've been surprised at how much electrical power the gas heater (and gas clothes dryer) consume. Spinning a non-trivial sized electrical motor consumes a non-trivial amount of electricity. Funny, that.