Hi all,
I'm new here, but thought I might add my two cents if people are interested in physics books that are interesting to kids.
Russell Stannard has three that my DS(now 8)got into a while back: "The Time and Space of Uncle Albert", "Black Holes and Uncle Albert" and "Uncle Albert and the Quantum Quest". Also, Stephen Hawking co-wrote two books with his daughter Lucy (I believe the story is they wrote them so they could explain to Lucy's daughter what Grandpa did). These are fun: "George's Secret Key to the Universe" and "George's Cosmic Treasure Hunt".
For kids that are more serious about their physics Larry Gonick has a cartoon style textbookish work titled (aptly enough)"The Cartoon Guide to Physics". He also has a good one on Chemistry, and another on Genetics. DS is now cracking the American History by Gonick, and we'll see how that one goes.

I hope this helps someone else who is looking for suitable and fun material for their unique child! I'd love to hear if anyone else has any suggestions... I'm sure my boys will love the link previously posted.