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.