by Scott Westerfeld
I've really enjoyed plenty of Westerfeld's books, and I like this one, too. Can't say it was my absolute favorite of his, but it's still a decent read. His books are always adventurous, quick-paced, and suspenseful, fun YA books.
This one deals with what is "cool" and how it gets that way, and how the whole thing is a scam to get you to spend money. Interesting idea, and maybe not too far from the truth (except the truth isn't nearly so cool as the story he spins here).