It's Android app week. Multi-tasking is one thing that makes Android great versus the Iphone, but it also leaves programs running in the back ground which can kill your battery life. This is where Advance Task Killer comes in. A.T.K automatically kills programs you are not currently using. It gives you the ability to ignore programs you never want to kill, and it allows you to set up the frequency of how often to free up memory.
From my own experience and setting A.T.K up for family and friends I would say you may see up to three hours of improved battery life by using this app. Just make sure after putting it on your phone that the first program you add to the ignore list is A.T.K itself. That way when you restart your phone A.T.K will already be running.