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.
Benchtop Power Board Kit Hookup Guide
Need more power? This Benchtop ATX Power Supply Kit should help give you the boost you need to power those energy hungry projects.
Blynk Board Project Guide
A series of Blynk projects you can set up on the Blynk Board without ever re-programming it.
Wireless Joystick Hookup Guide
A hookup guide for the SparkFun Wireless Joystick Kit.