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.
12V/5V Power Supply Hookup Guide
In this tutorial, we will replace the 12V/5V (2A) power supply's molex connector with two male barrel jacks adapters.
Hookup Guide for the SparkFun RedBoard Artemis ATP
Get started with the RedBoard Artemis ATP - all the functionality of the SparkFun Artemis module wrapped in the Mega Arduino Footprint
Fuse Breakout Board Hookup Guide
Protect your project by adding a fuse in your circuit to save it from molten destruction.
ATX Power Connector (4-Pin) Breakout Hookup Guide
Do you need to power a project with 12V and 5V from one wall adapter? The ATX power connector breaks out the standard 4-pin computer peripheral port for your 12V and 5V devices!