Actually, not to hijack this thread, anyone knows how much current an deep sleep Arduino Uno draws?
I measured my Arduino Uno at 42mA when running.
With the MCU in power-down mode (the deepest sleep mode), it still draws 31mA.
The ATmega328P microcontroller alone uses around 0.1µA in power-down mode.
I'm currently designing an Arduino-based data logger using an ATmega328P on a custom PC board. There are one or two other components that draw small idle currents as well, but when it's sleeping the whole board draws < 5µA. A "sleeping" Uno draws 6200 times more current.