BossComing is useful and extremely fast. It will hide all windows in a snap and will show the desktop as if nothing happened.
From now on and thanks to BossComing you'll be able to check Facebook, read the newspaper online and chat with your friends while you are in the office. If the boss come in or goes towards your table, just click the wheel button of the mouse and everything will disappear from screen.
When he'll go out, just click it again and continue what you were doing.
Finally, you can set passwords to restore desktop or set a program to be run when you click the wheel button, so that program will appear on screen when the boss comes.