Reducing Arduino Power Consumption
Contributors:
Alex the Giant
Alex the Giant 
Resources and Going Further
More information on low-power modes and options can be found in the datasheet for the 328P.
For more power-related fun, check out the following SparkFun tutorials.
Battery Technologies
The basics behind the batteries used in portable electronic devices: LiPo, NiMH, coin cells, and alkaline.
Wireless Joystick Hookup Guide
A hookup guide for the SparkFun Wireless Joystick Kit.
Hookup Guide for the SparkFun RedBoard Artemis
Get started with the RedBoard Artemis - all the functionality of the SparkFun Artemis module wrapped in the familiar Uno R3 footprint
Hookup Guide for the SparkFun RedBoard Artemis Nano
Get started with the powerful RedBoard Artemis Nano