This is something that we should all be able to do!
How many times do use Google in a day? A week? A month? A year? Do you ever think how much energy you use by just using Google? Mark Ontkush, a leading expert in "green" computing says that if you took the amount of time on Google of every person in the world and added the time together it would add up to 550,000 hours every day on average!
Mark thought a bit more about this and told Google about his findings. He also calculated that if they put a black background on Google it would save 3000 Megawatt-hours a year. In the end this would save about $75,000 a year of electricity for the world. You could say that isn't a lot of money but that could go to a good use. Google considered this and customized a new search engine called Earthle. It uses a black background and green writing (which is much more energy efficient). If everyone switched from Google to Earthle, the calculations above would become reality.
All this can be done simply by typing www.earthle.com instead of www.google.com (oh no! one more letter!!!) So the next time you are about to go to Google, think (and go to) Earthle. Even by making your homepage Earthle the black background is probably more energy efficient than your regular one.
Try it out!