I have a friend who is looking for a simple (and inexpensive) RPG his kids and their friends can play that could easily be adapted to a Harry Potter/Hogwarts setting. I know there are all sorts of online HP roleplaying sites, but my friend is looking for a tabletop RPG. The child who would be GMing this is about 12, very bright, and reads a lot. The players would be slightly younger (8-11) and are "pretty average kids."
I don't think there are any official Harry Potter RPGs and have no idea what rules would be simple enough for this age group. If any readers have some ideas, I'd love to hear them as I'm drawing a blank on this.