The best birthday present for a 13 year old girl is the complete set of Anne of Green Gables and the Emily series by L.M. Montgomery. And the movie to go with them. But I'll bet you any money your daughter has already read the books and seen the movie. So...a pony.
@Amy Chisnell Wow. How did you know she'd already have the Anne of Green Gables books? Oh yeah-librarian's kid. :P I think she's seen some of the Anne of Green Gables movie (starring Megan Follows and Colleen Dewhurst). I loved them, but I'm not sure how she feels about them. I've never read the Emily books - I'll have to look into those. Pony?! Thank goodness she can't see that suggestion! The puppy we got this summer is quite enough to keep us on our toes. As it is, I am the one getting up early to walk the dog. I don't think I could handle mucking out a stable, too. :)
I suggest getting her into a creative hobby and buying the supplies as her gift. Painting, pottery, sewing, knitting, etc. Kids love being creative and she can start on her holiday gifts now. Who doesn't love a homemade present?
I can't believe a Pony isn't an option. Every kid should have a Pony. Actually, you could probably train a pony to walk the dog. And you wouldn't need a stable - he could live inside, as long as you get him the right footwear (http://www.guidehorse.org/horse_sneakers.htm )
Emily of New Moon is the first book in the Emily series. I preferred Emily to Anne. They never made her into a movie but there was a tv series based on the character, I believe.
The Engineering Computation Pads was the first real gift my kids gave me for my birthday. My kids must have been 6, 4, and 2. They would watch me work at home while asking me questions and I always use green engineering paper. And to this day for Christmas, Fathers Day, etc. my kids will get me, STAEDTLER Engineering Computation Pads.
Some board/card games that my son and his friends loved at that age (and still love) were Apples to Apples, Munchkin, and Settlers (I'm assuming that, if she's like her mother, she enjoys smart, nerdy fun). :)