There are a number of cool options that can be found by holding down the option key as you click around in Mac OS X, but one that is really useful is a shortcut to turn Do Not Disturb on and off.
Try this real quick. Hold down option and click on the notification icon (far right of your menu bar). Depending on your settings, the icon will either turn grey, meaning Do Not Disturb is now active, or it will turn black, meaning Do Not Disturb is has been turned off.
If you use this feature, it can be a pretty handy little shortcut. Enjoy.