This 5 Volt 2 Amp power supply runs off a single Li-Ion cell and is charged via micro USB. It has 2 USB type A outputs.
The input can provide power to the output and charge the battery simultaneously. When the input power is removed, the battery supplies power to the output.
An ATtiny45 microcontroller handles power management. There are two LED indicators for status and battery charge level.
At idle, the board draws less than 2μA!
More details are available at www.flashcandy.us/products/little-nugget-v2