Jason Torchinsky is a guest blogger on Boing Boing. Jason has a book out now, Ad Nauseam: A Survivor's Guide to American Consumer Culture. He lives in Los Angeles, where he is a tinkerer and artist and writes for the Onion News Network. He lives with a common-law wife, five animals, too many old cars, and a shed full of crap.
If you were a mad scientist evil genius who happened to only be interested in advertising, it would make sense for you to come up with this: a way to brand the moon with a giant ad. You'd call the UN, get on that big screen, and blackmail the world into caving into your demands, otherwise you were going to deface the moon with a colossal ad for Gold Bond Foot Powder or Cool Ranch Doritos.
This idea has been around a while, and I have no doubt it's possible. The only way I think this could be justified is if the advertiser paid each and every moon-gazing person some amount to do this, since the visual image of the moon in the night sky can be thought of as public property; you can't legally throw a billboard up on land that you don't own, so I don't see how this is different. But, if someone wants to rent the moon from the collected people of Earth, who knows? Feel free to make us an offer; someone's almost always here.