We've come to rely on blinking dots and obscure icons to tell when a device's battery is low, but the human face is just so much easier to read and decipher. You wouldn't want to have to flip a baby over and check a set of LEDs to see if it was happy, so the expressive face on this Mr Pow backup battery reflecting its charge level just makes sense.
While the $40 Mr Pow starts out with a big LED grin on his face, as he tops off your devices with his 3500 mAh battery and loses his charge, he'll eventually start frowning. That's when you know it's time for him to give him more juice, and possibly a hug. [Spinning Hat]