When I saw the first billboard it seemed like a joke, but then I saw a second and figured this thing was real.
Some company (and I am not going to help then be referring you to their website) is advertising on the moon. And they will help you do the same (if you pay them).
The next question is obvious: What's next, the sun?
Skywriting is cool. I'm down with the Goodyear Blimp. But are we really going to deface the moon?