Secret Encourager

Our new pastor is so fantastic, I am almost beyond words to describe how wonderful she is! We have a large confirmation class for our little church this year, 9 kids! Pastor Alice borrowed an idea from her dad (also a pastor) to support the confirmands journey. It's called "Secret Encouragers". Each kid has an adult - they are not told who - who will pray for them, as well as leave them notes of encouragement in their special mailboxes. I signed up to be one of the adults, and have purchased a few cards to get started. What I am looking for is some ideas. Maybe a book or movie - oooh "Facing the Giants" is a good one! - to leave in her mailbox, that might be fun and supportive. She's a seventh grader, so things have to be cool, ya know. Anyone got a thought?