If you have a Mac PowerBook, MacBook Pro or MacBook, you can use your computer with an external monitor without having to use the screen on your computer. I prefer using my Macbook Pro with only an external monitor since it saves the life of the screen on my computer, and my Mac is quieter when I run it with the screen closed.

To run in this mode, you need to hook up an external monitor, keyboard, and mouse. Then close the lid of your computer, this will put your computer to sleep. Then wake up your computer by hitting the keyboard. It'll come up using the external monitor as the main monitor for your computer.