Check out the latest experiment from NASA: The High Definition Earth Viewing (HDEV). These cameras are exposed to the radiation of the sun, which will allow scientists to understand how this affects them.
These ISS cams are pointed down to our planet at all times so we can see some really amazing images. Maybe you can also catch a UFO!
If the stream is down (the screen will be grey), take a look at some of the top footage recorded so far: