A great site for HP activites that we used when my son read the first book is at http://www.mce.k12tn.net/reading18/harry_potter.htm
It has an activity for almost every chapter and also a little reading comprehension quiz.
My son read book on in the HP series at 6 too. He still loves to be read to and i believe children that age should still be read to no matter how bright. (And of course on their own too) So anyway, we read it together, He read one page and then I'd read the next and so on. We still read that way, he's seven now, and has read the first 4 and a half and lost interest because of all the parts about girls and boys and just being frustrated at the story at that point..because the things that happen at that point make you mad. : )