UPDATE: Wow, lots of great suggestions here! RP for anyone in the same boat.

Anyone have any suggestions for books my 11 year old might appreciate to scratch the Harry Potter itch? They read the first book in school and enjoyed it, wants to read the rest but I've soft blocked them from my home and I don't want to use library resources on them (thus encouraging library to buy more copies...). I know of some good fantasy series but they're a few years out from being able to appreciate them yet...