iOS (Jailbreak): If you're an iPhone power user, the battery will never last long enough. BattSaver is a jailbreak app that automatically toggles radio signals, Wi-Fi and more to save juice.
BattSaver comes packed with four separate battery-saving strategies: normal, aggressive, ultimate and custom. The default settings turn off Wi-Fi or mobile data, depending on what you're doing. The custom setting is far more interesting; you can set up BattSaver to automatically turn off all radios when your iPhone is sleeping, and then have it wake up every 15 minutes to check for notifications. You can automatically turn off data when Wi-Fi is on, or manage your battery when it's below 15 per cent. It essentially automates different ways to increase your iPhone's battery life.
Your battery life will vary depending on your settings, but I saw a little improvement after tinkering with the custom settings. More interesting, perhaps, is the fact you can use BattSaver to automate your "off internet times". With a little tweaking, you can ensure nobody will bother you after work, over the weekend or when you're on holidays. BattSaver is a $US2.99 download from the Cydia store.