Editor: Display Rotation Menu provides an easy and quick way to set the rotation of your monitor. And best of all, it's free!
Press Command-Option-Control-0 to put the main display into landscape mode. This is handy when you switch to portrait mode and there are too many menu items to show the Display Rotation Menu.
OS X does not support rotation on all graphics card / monitor configurations. If OS X can not support rotating your display, then "Rotation Not Supported" will be displayed in the menu.
