While you're waiting for Harry Potter day to come along, check out this list of others to try from ALA. I'm really glad to see Mister Monday make the list (since its not on the list we give out at our library but I've been promoting it to anyone who asks for a Harry type book)
Books on the list that I loved (or at least would recommend)
Baum, L. Frank. The Wizard of Oz.
Billingsly, Franny. The Folk Keeper
Colfer, Eoin. Artemis Fowl.
Funke, Cornelia. Inkheart.
Nix, Garth. Mister Monday. (Keys to the Kingdom)
Snicket, Lemony. The Bad Beginning. (A Series of Unfortunate Events)
Stroud, Jonathan. The Amulet of Samarkand. (The Bartimaeus Trilogy)
Eager, Edgar. Half Magic.
Ende, Michael. The Neverending Story.
L'Engle, Madeleine. A Wrinkle in Time.
Lewis, C.S. Chronicles of Narnia.
Levine, Gail Carson. Ella Enchanted. [one of my new favorite movies, haven't read the book]
Nix, Garth. Sabriel. (Abhorsen Trilogy)
Paolini, Christopher. Eragon.
Pullman, Philip. The Golden Compass. (His Dark Materials)
Tolkein, J.R.R. The Hobbit.
Ones that were on my to-read list already:
Black, Holly. The Field Guide. (The Spiderwick Chronicles) [I listened to one of the later ones in the series]
Cooper, Susan. The Dark is Rising. (Dark is Rising Sequence)
Duane, Diane. So You Want To Be A Wizard.(Young Wizard Series)
Sage, Angie. Septimius Heap, Book One: Magyk.
Yolen, Jane. Wizard's Hall.
and now I'll have to go check out the rest :)