I have a nine-year-old daughter too! She really liked Percy Jackson, lukewarm on Harry Potter (I think the popularity turned her off, actually). Here are some of her current faves:
The series that begins with The Name of This Book Is Secret, Pseudonymous Bosch
A Series of Unfortunate Events
Septimus Heap series (first book is Magyk)
The Worst Witch books -- sort of proto Harry Potter, about a girl witch at boarding school
His Dark Materials series, Philip Pullman
She hasnt' read the series that begins with The Sea of Trolls, by Nancy Farmer, but those are supposed to be excellent and they're HUGE.