From Oleg I. Galkin:
Black Screen is the program for people that spend long hours working with a computer. It allows to give your eyes a rest and reset your attention.
Give your eyes a rest.
A simple key press will turn your screen black. It's much faster than turning your display off and on.
It's hard to stay focused when working on a computer. That's why you often want to reset your attention - divert attention for no more than a few seconds. To do that, you switch to reading news, browsing the web, watching videos or social networking. But more often than not, you get stuck there; instead of a few seconds, it takes minutes. And it's hard to get focused again. Using Black Screen you can reset attention without getting stuck. After turning your screen black, press a key and see an awesome random photo for a few seconds. Press the key many times to keep yourself amazed for a while with the stunning slide show. Then, remove Black Screen and continue to work having your attention refreshed.