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.
INA169 Breakout Board Hookup Guide
How to interface with the INA169 Breakout Board to measure current.
FemtoBuck Constant Current LED Driver Hookup Guide v13
The FemtoBuck board is a high-efficiency, single-channel constant-current LED driver.
How to Build a Remote Kill Switch
Learn how to build a wireless controller to kill power when things go... sentient.
Single Cell LiPo Battery Care
This tutorial will go over how to safely charge, connect, disconnect, reinforcing the cables, and handle single cell LiPo batteries.