App Stop is a great utility application for Symbian S60 5th Edition and Symbian^3devices. It lets you close all your running tasks and applications instantly, and also allows you to shut down hidden background tasks that are not visible in the built-in task manager. Adding the App Stop shortcut to the homescreen lets you instantly shut down all applications with two presses of a button. Hit the jump for download links.
You can download App Stop free for your Nokia S60 5th Edition handset here, and for your Nokia Symbian^3 handset here.