Dude! Free power!

In small quantities.

The Perpetua Power Puck is a solid-state thermoelectric power supply with no moving parts, that can run low-power electronic devices off of ambient thermal gradients as small as 1°-2° C.  The Power Puck weighs 60 grams and can supply regulated voltages from 1.5V to 3.3V.

The Constitution and the Magna Carta

cipherpunk discusses the differences between the two, and how the government has turned a short and strictly enumerated list of only seventeen things it is allowed by the Constitution to do, all other things being forbidden to it, into "We can do whatever we want".