I am trying to find some great reads for her and it has been awhile since I was that age.

Theresa

Anne of Green Gables series

Catherine, Also Known as Birdie

Judy Blume's books for more mature readers, such as "Are You There God, It's Me Margaret?"

Mark Twain- Huckleberry Finn

The Hobbit series

To Kill a Mockingbird

Has she read the Harry Potter series?

I think I started reading Sue Grafton's alphabet mysteries around that age, starting with A is for Alibi.

Jane Austen?

I'm drawing a blank. What sorts of books does she like?

Johnny Tremain

Island of the Blue Dolphin

King of the Wind

The Trixie Belden mystery series

The Oz series (there were many other books in addition to The Wizard of Oz)

Those were some that I enjoyed at that age.

Scott Westerfeld's series:  Uglies/Pretties/Specials/Extras

Any of the books by Sarah Dessen are good. 

The Shadow Children series by Margarat Peterson-Haddix would also be good for that age.

I would recomend the Maximum Ride Seried By James Patterson. There action and humor.

http://www.paperbackswap.com/tags/index.php?type_id=1&tag_id=42853 This will take you to all 4 books

I just finished Ghost Boy by Iain Lawrence and think a girl of thirteen--and everybody else on Earth---would absolutely love it.  I'm a few decades past 13, and I simply could not put it down.  It's young adult.  And though the main character is a boy, he is very relatable:  he's 14 and an Albino and so is very uncomfortable in his own skin.  He's sad but very sweet, friendless, with an unhappy home life, and he one day he manages to join the circus where he is befriended by "The Freaks".  Each character is thoroughly endearing, the writing is vivid and fast-paced, and the story is excellent--fun, moving, happy and sad.  I really can't say enough about this book!!!   It was a great discovery and I just want to sing it's praises. 

my sister is almost 13 and has been reading the Nancy Rue "Lilly" series and loves it.  Her friends are also reading Janette Oke's Love Comes Softly series and Frank Peretti's childrens's books, the first in the series is called "The Hangman's Curse"

Lois Lowry's trilogy, THE GIVER, THE MESSENGER and GATHERING BLUE.  Written for teens, but adults would enjoy them too!

The trilogy by Madeleine L'Engle 'A Wrinkle in Time', A Wind in the Door', 'A swiftly Tilting Planet'

'Kim' by Rudyard Kipling

'The Velvet Room' by Zilpha Keatly Snyder. Or anything by her. Alot of her books are in print or recently in print. I'm not sure about this one, its one of her older ones.

Lots of other good fantasy out there too. The Riddlemaster trilogy by Patricia McKillip, or just about any of her other fantasy books.  Also Patricia C. Wrede is a good ya fantasy writer. In sf, Ben Bova's young adult books are really good. And of course, the Earthsea Trilogy by Ursula K LeGuin. Any of Andre Nortons Fantasy or sf is fine for a young person that age.

A warning about Judy Blum... she's a wonderful children/young adult writer, BUT she also writes explicit adult  books under her own name, so it gets a little confusing sometimes, figuring out which one you have, without being able to read it. I would suggest going to a book store with knowledgable clerks, and taking a look see at their shelves first. You can always make a list and look for them here for her.

Jacky

My 14yr old daughter loves the Warrior Series by Erin Hunter and the Redwall series by Brian Jacques.  I second the Maximum Ride and Harry Potter series as well.  Erin Hunter also has a series about bears called the Seekers.

Trixie Belden series is wonderful.  Also Nancy Drew

Check out "The Dork Diaries" by Rachel Renee Russell.  It's just been published.  My DD is 11 and read it, although I believe the main character is about 13 or 14.  It was a very good book about a new girl in school who wants to be popular.  Sounds predictable but I read it too, and even I enjoyed it.

I've also just read "Life In The Fat Lane" by Cherie Bennett.  Wow, what a good book.  The main character is a 16 year old, older than your daughter, but I still think she might like it.  The main character gains weight very quickly because of a disease, not because she overeats.  Before the weight gain she was a very popular girl, prom queen, model thin, etc.  And when she started gaining weight, she found out what it's like to live on the other side of the coin-plus she has stuff going on in her family she has to deal with.  A real good book!

Oh and Deborah-I second your opinion about Trixie Belden!  :o)

I highly recommend the series Cirque du Freak. :} It's good, creepy fun for younglings.

By the way, I am an older teenager, and I read that when I was about 13.

I liked Nancy Drew  when I was that age

What is her reading level? At 13 I was reading "college" level books, but depending on your daughter, that might not be the route to go. I would whole-heartedly recommend any of Scott O'Dell's (Island of the Blue Dolphins author) books about women. All of the girls/women are strong and empowered. Witch of Blackbird Pond was great, the first few dragon books by Anne McCaffery, anything by Madeleine L'Engle...

If you have a woman-run bookstore nearby, they probably have some good suggestions for books with positive female rolemodels.

I just got my step-sister "Derby Girl," and while it does have some profanity, she loves it a lot (has already read it several times), and it's shown her a great character that doesn't fit in and doesn't particularly want to, but finds a group to feel a sense of belonging with (roller derby bad-assery).

The Dragon books with music in the title are aimed at YA.  Dragon Drums?  Dragon Song?

Watership Down.  The books by the English Vet, James Herriot?  (Can you tell at that age I'd rather read about animals than kissing?)

Ray Bradbury's Martian Chronicles.  The Firebird series of SF / fantasy stories.  (Good place to find authors.)