For those of you who have young girls who enjoyed the Harry Potter series, may I recommend the author Tamora Pierce? She has several different series of books, all in that fantasy-magic kinda theme. One of my daughters is just poring through her stuff!
For instance, there is "The Immortals" series, 4 books in all, with the first book entitled "Wild Magic." It's about a young girl with a knack for horses that turns out to be downright magical. From the back of the book:
"Set in Tortall during the reign of King Jonathan III and Queen Thayet, 'Wild Magic' is the first book of The Immortals Series, which chronicles the time when the world is invaded by immortal creatures and a girl is born with a magical gift that could restore the very balance of nature."
I read the first couple chapters before my daughter tore the book from me. I gotta go grab it back