This is probably old news, but I found a neat feature whilst looking at this: http://macmost.com/downloads/MacMostKeyboardShortcutsSnowLeopard.pdf
⌃ ⌥ ⌘ 8 Reverse screen
So, for all you old-skool coders who prefer white-on-black, and it sort of looks like the unity dark theme, this might be for you 
This is also a great prank to play on any Mac user. Just casually walk up to their keyboard when they’re not watching…
I had my aunt and my friend’s sister freaking out.
Go to the Apple Store, do it to all of the Macs, and then leave. The Apple people will have to go to settings for each one to turn it off if they don’t know the shortcut.