F.lux adapts your display to the time of day
As time passes, F.lux checks the status of the sun in your zip code or latitude, and adjusts your display's color temperature accordingly. As a writer, I love the extra bit of environmental awareness it offers. As a designer, I would probably be utterly annoyed by shifting display settings. Good thing there's a handy "turn off for one hour" feature you can use to switch back to your regular whitepoint while you're working with color.