One of the joys of using a laptop is portability. But as anyone who has tried to use a laptop outside in the sunlight knows, the screen is hard to read.
Which brings up this keyboard shortcut: CTRL-OPTION-APPLE-8, which switches to "inverse" mode. Basically, it inverts all the colors on the screen. Try it -- I'll wait. Notice this this is "8", not "F8".
See? Scary, huh? Great for using your laptop outside, though.