Android: Maintaining a solid data connection eats up a lot of battery power, and turning it off to save juice usually means remembering to toggle it back on again. InterNETmittence is a free app that toggles Android's data connection for you, but also remembers to turn it back on later.
It turns the connection on and off in a cycle, saving battery while it's off and allowing apps to grab their data, like emails and calendar updates when it's on.
The best times to use this app would be while sleeping, and while in a big office building that wrecks your phone's data reception. Voice service remains untouched so you won't miss calls, but the phone won't waste power trying to connect anything else unless it's in an "on" window. To make sure there are no surprises, it doesn't kill the connection if you happen to be using the phone, either — it waits for the screen to lock first.
The "Pro" version of InterNETmittence opens up two options that skip the time interval. You can schedule "quiet hours" that keep data turned off for extended periods (useful if you've got a consistent sleep schedule), and you can set the app to kill the connection whenever the screen is shut off — for keeping extra-tight reigns on power consumption.
For other tips and useful tools to deal with power consumption on Android, check out our post on how to get better battery life.
InterNETmittence [Android Market]