Anne Fine's Charm School is a nice, light-weight teen book about appearance and fashion being far from everything that matters; it resonated nicely with a comment from a panelist on Any Questions yesterday wishing that we thought more about the way people act and less about the way they look. I wish the way you look wasn't such a weapon for people; it would be nice not to feel so insecure about something so fundamentally irrelevant.
Diana Wynne Jones: The Merlin Conspiracy might well be aimed at the same age range but it's a much meatier book. Told in alternating narratives by two of the characters, it's an excellent adventure mystery with a nice mix of mythic resonance, nifty parallel worlds and real people with real problems. Some of it really resonated for me and all of it was an excellent read.