Is there a way to force Mac OS X to close all the applications when restarting?

I sometimes shut down my Mac, and I cannot wait it shuts down because I am urgently requested to do something in another office that would require some hours. In some cases, an application that opens a dialog box asking if I really want to close the application blocks the shut down, and when I return I find the Mac still on.
Is there a way to force the Mac to close any applications, instead of blocking the shut down?

Solution 1:

All you need is to open Terminal.app and type:

sudo shutdown now

That way the system will be forced to terminate all open programs, ignoring any unsaved file changes.

So, in order to be able to launch it via the desktop, you need to open Applescript editor, and type:

do shell script "shutdown now" with administrator privileges

Save the script as an Application, and drag it in your Dock, or somewhere where you'll find it instantly.