Saturn's moon Phoebe
The Cassini probe passed within 2000 kilometres of Saturn's outermost moon Phoebe on June 11 2004.
The above picture was the best Voyager 2 could take of it as it passed further than 2 million kilometres from Phoebe. Cassini took absolutely breath-taking photographs of this moon.
You can see where soil and detritus has slid down the sides of the craters. Phoebe is one of the darkest objects in the Solar System as well. Makes a stark contrast to its fellow Saturnian moon, Enceladus, which is one of the brightest.
As far as I know, all NASA images are in the public domain. Still, credit where credit is due. More excellent pictures can be found here.