There used to be a stock task killer with Gingerbread on the Razr Maxx, but they got rid of it with ICS. Task killers are generally not helpful in Android, because many apps will restart after you stop them. If you have a task killer set up to automatically stop certain apps, the constant cycling of apps turning on and then off can actually drain your battery more. The only reason to use a task killer is if there's an app that you suspect is malfunctioning (and thereby taking up excess CPU cycles), and you can do this simply by going to Manage Apps, and selecting Force Stop.
i go in and close them out through the home screen. when u are on yourr home screen hold the home button and it will show you a list of apps that were running and swipe them off of the screen to close them
That actually doesn't close the app. Long pressing the home button just brings up a recent apps list, not a task manager. You can tell it doesn't close the app by opening something like Pandora, playing some music, then swiping that app away. The music will keep playing, meaning that the app didn't close.
Sent from my DROID RAZR using Android Central Forums
Good question. It just de-clutters your recent app list, I guess. I suppose it might be useful if you use the recent app list a lot to start your frequently used apps, and if there's an outlier in there, you can swipe it away.