I don't know. Skywriting?
Mabye carving an ad into the moon...
Well, probably something a bit more subtle than that, but it's all I can think of. Wow. I'm being really unhelpful, aren't I? Sorry. I do love this series, though, and the last book was- urgh! Amazing, but so frustrating!
Anyways, not very helpful, but at least something more is on there now. And, you gotta admit, not the worst waste of your time.