Oh, lord, I must've seen Ghostbusters a bazillion times. *G* And you know, I still love that movie. :-)

I definitely recommend the first three Diane Duane books. They're not set in a magical academy like Harry Potter or Worst Witch, but it's still a cool universe. I'm pretty sure Rowling's flying car from CoS was borrowed from inspired by the feral car in Duane's first book. My personal favorite is the second book, Deep Wizardry, which is mostly set in the ocean and features an ancient megaladon shark (named Ed, no less) as one of the supporting characters.