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.
It doesn't require installation. No settings are stored in the Windows Registry or file system.
Just download and extract the ZIP file and create a shortcut of "CloseAll.exe" file which can be later put on Desktop, in Quick Launch toolbar or pin to Windows 7 Taskbar.
Download Link
Homepage
You can also prevent certain applications from being to be closed by Close All by appending -x="application_name.exe" at the end of the "Target" string in Properties of the CloseAll application shortcut. You can separate multiple values with "|" (pipe) as well.