Altoids USB Charger
I came across instructions to make a USB charger from an Altoids tin on BoingBoing. Mine's rather scuffed, but the next one will be prettier.
One innovation worth considering if you try this yourself: instead of buying a bare female USB socket, use the kind that's meant to plug into a motherboard. You'll save a bunch of soldering (the female socket already has positive and negative wires), and you can screw the socket into the tin instead of soldering it -- which means it's easier to move your electronics when it's time for a new tin.