The Rosetta probe mission is an exciting one. It was launched in 2004 with the intention to orbit and land on a comet (specifically, 67P/Churyumov-Gerasimenko). In the meantime, it's passed by Mars and a few of the stranger asteroids we've studied, grabbing some great photos in the process. It's orbiting the comet now. Take a look at the new photos. For reference, the comet is only about two and a half miles long.

See also: the entire trip.