I think these are a good idea. They aren't so widespread out here in Aus yet though. I saw one in the father-in-laws house when we visited last year, it also showed cost estimations.

I try not to waste too much power, but without being overly anal about it. I care a bit about the environment, and yet I also want to know what's the highest consumption you could get the thing to go up to? Like if you switched EVERYTHING on all at once.