Inverting your screen

After a few hours of work on the computer, my eyes get tired of starring at white text background. An awesome shortcut that is quite unknown is "Ctrl-Option-Command-8". It temporarily inverts the colors until you use the same key combination again. The black text background looks great for a few minutes and it is much easier on the eyes. I tried taking a screenshot to show you the effect, but unfortunately, the screenshot doesn't show the difference. It seems that it only changes what you see and nothing permanent (such as screenshot, etc..).

Edit: Here is an inverted screenshot submitted by Oliver Isaac. Basically it is a normal screenshot that was inverted in Photoshop or any image editing program. Thanks Oliver!