One of the latest missions from the ISS is kind of amazing. The High Definition Earth Viewing (HDEV) experiment consists of four cameras that have been attached outside of the ISS. You can watch the Earth turn from space, live, 24 hours a day.
The cameras point down at Earth at all times, which makes for some breathtaking images. The feed will sometimes go down as the signal switches between the cameras, and it is hard to see when the ISS is on the dark side of the planet. If the cameras are down, the screen will be grey.
Watch the live stream here: