Phobos, Mars' largest (but still tiny) moon, is doomed. Hanging in a low orbit, tidal forces will eventually break up the moon, forming a ring around Mars. Hang on for 100 million years or so, and you can see this ring, too. Phobos is likey a captured asteroid, and this high-res view of the moon from NASA's Mars Reconnaissance Orbiter shows it's resemblance to other asteroids that have been photographed at high resolution.
The large bowl-like feature is Stickney Crater, named after Chloe Angeline Stickney Hall, mathematician, and wife, of astronomer Asaph Hall. For a large (13 Mb) photo of Phobos, click here. The large (3.5 Mb) photo of Stickney crater is here.
Moon over Whidbey Island.