@W3bbo: just to set the numbers straight, according to FAO, the energy required by a light or sedentary worker for 24h is 1.53 times the Basal Metabolic Rate (i.e. the energy required to lay awake in a well defined resting condition). By comparison, a heavy worker requires 2.25 times the BMR.
Once you consider that the brain consumes pretty much the same amount of energy regardless of its activity (or the quality of such activity) and that the BMR varies a lot with age, gender and body weight, you get enough evidence that thermodynamics is not a good way to measure effort.
@evildictaitor: while I'm in nitpicking mode: you keep quoting the comparison between the net worth of the top 400 with the bottom 50% of the population. While that number is impressive, I don't think it's very relevant as even redistributing all that wealth wouldn't make much of a difference (even more so once you consider that you can only redistribute it once). The figure I would use from the same source is the fact that the top 1% of the US households earns the same amount of money of the bottom 50% combined. While the ratio is a lot less spectacular, those are incomes that could potentially pay higher taxes every year.