Battery life is often overlooked when building projects, especially for beginners. This tutorial takes you through the setup of power saving modes for the Arduino. Utilizing the watchdog and sleep functions, they put the chip into a hibernation mode between cycles. An optimum configuration could take your battery life from 4 days to about 3 years.  For a lot of you, this is old news. But for the rest, this is really good stuff. You can download a sample application from the site that mimics the singing of a nightingale when the sun goes down.

Gizmodo has posted a guide for extending the battery life of your shiny new iPhone 3G. Apple is notorious for pushing products with unimpressive battery life, and the new iPhone is no different. The battery isn’t user-replaceable, which means you can’t keep a spare, and the energy needs of the 3G chipset adds to the problem. Apple provides some useful tips on maximizing battery life for your iPhone. The tips include common sense advice that applies to nearly all electronic devices – turning down the brightness on your LCD screen, turning off radios not in use like Bluetooth, WiFi, GPS, and 3G, and setting Auto-lock to a minute or less will keep your devices running smoothly for longer.

We like to carry an extra USB battery like this one; you can also make your own like this one with an Altoids tin.