Recommendations??

I have a son who is an avid reader (yay!).  He's almost nine, but has been reading at a 13-year-old level for about a year now.  And finding books that both interest him and are appropriate to his reading age is proving difficult.

We go to the library every Saturday, and he checks out anything between 10 and 17 books.  And he's always read all of them before the next Saturday.  I look at these flimsy little paperbacks and it's no wonder he reads them so fast.  But when I try to give him bigger, more complex books, he struggles with them because he's not that interested in the subject matter.

So I thought I'd ask my wonderful blog readers if you have any recommendations of books that would interest a precocious 9-year-old reader.  He's read the first 3 Harry Potter books, all the Willard Price adventure books, The Hobbit and a lot of other things.  He seems to like fantasy and adventure a lot, which I struggle with a little because I've never enjoyed fantasy, even as a kid.

I'll let you know how he gets on with whatever you recommend...