Close all app in 1-click

This tool helps you to close all running applications with one click. It does not use system resources because it only flashes a “close” signal to all open windows on the desktop and then ceases. Just place a shortcut to the tool in the Start Menu, Quick Launch or elsewhere.

You can always add a hotkey to this shortcut. It is really very handy if you are running ~20 applications and want them all to quit instantly. It works just as if you were pressing the close button for each application.

Get it here
Source: its developer