I thought this photo of Saturn from above was the coolest thing ever until I saw this:
That is a picture of a comet. Not in the background, mind you, the foreground. It was taken by the Rosetta spacecraft, which is currently in orbit around said comet (which is burdened by the unwieldy name of 67P/ Churyumov-Gerasimenko). The scale is just under a meter per pixel. If there was a human walking around down there, you could see her (just barely). The photo is about 800 meters (half a mile) from side to side.
In the next few days, a lander will detach from the spacecraft and, if all goes well, will actually land on the surface of the comet. This will be only the fifth place in the universe from which we will have photos from the surface, the other four being the moon, Mars, Venus, Titan (one photo), and of course, Earth.
My nominee for second-coolest-thing-ever is this awe-inspiring backlit shot of Saturn:
You can find more of these at the Cassini images hall of fame.
It is truly an amazing universe we live in. (Too bad we're blithely destroying the best part of it.)