"Negative Display" feature

Did you know that if you hit Control+Option+Command+8 you will make your display appear as a negative image (at least in 10.2.8)?
Anyone know how long this has been a feature of the OS?
Also, what other arcane key combinations that do equally unusual things do you know about?

Peyote said:

It's part of OSX's options for the visually impaired. Not an arcane joke or "easter egg", but an actual option that has a purpose. It's also very cool looking.

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One of our employees accidentally hit this combination on their Mac yesterday afternoon, and we stumbled across the solution.
I see how it could come in handy if you have a hard time with the contrast of a web site or something. I'm going to have to view a halftone as a negative and reverse the screen to see if it looks relatively normal or not.