Most recently, it has been photographing Lutetia, and this one was featured on The Planetary Society Blog:
Not only do we get a close-up look at an asteroid, but Rosetta also happened to catch something else in this shot. If you said: "Hey, that looks like Saturn..." you're absolutely correct!
This shot reminds me of how empty our solar system really is. We generally see picture of planets, their moons, and stars in the distance, all of which make it seem like the universe is filled with all kinds of objects. And it is, but there's also a LOT of empty space in between those objects. This shot illustrates that beautifully.
You can see more photos of Lutetia on the Rosetta Blog. They're all incredible to look at.