The standard orientation of our computer screens is generally horizontal (also known as landscape) but monitors placed in portrait mode (where height becomes greater than the width) can be pretty useful for performing tasks that require lot of scrolling (like reading lengthy web pages).
Windows 7 includes a new option under Display Settings that can help you flip the screen from portrait to landscape mode (and vice-versa) without requiring additional software.
This may come very handy if you are using a dual monitor setup with Windows 7 where you want one screen in the default horizontal mode and other one in vertical mode for reading content.
You’ll still have to manually rotate the other monitor by 90 ° (as in this screenshot) but that’s a one time task. Hat tip Marcus.