Holy Saturn, Batman!
In perhaps one of the most beauteous pictures ever, this image was created from a mosaic of images taken by the Cassini spacecraft. If you're anything like me, you'll immediately download the massive 9000 x 3500 pixel image and add it to your wallpaper folder. Go ahead. I'll wait.
You should definitely check out Phil Plait's post about the image, where he points out and describes several of the interesting things included in this image, as well as linking to further reading on the subject.
Notably, there's an annotated version of the picture that labels Venus, Mars, the Earth-Moon system, and several moons of Saturn. As Phil Plait would say, click to enSaturnate: