Unhappy with your iPhone's battery life? Want to make sure you don't have to send it in for the dreaded $80 replacement surgery? Fear not, Apple's posted a completely obvious guide to getting the most out of your mobile. You know, amazing little tricks you never thought of, like putting it to sleep with the sleep / wake button when you're not using it. Don't worry, Apple says, "You will still be able to receive calls and text messages while it is locked, but nothing happens if you touch the screen." Sweet.