hi, you were asking about any books to help her prepare...there is a book (2 actually) from Joanna Cole, it's I'M A BIG SISTER (or BROTHER if you had a boy). There's also a series of New Baby books by Annie Kubler calls My New Baby...and it says that there's a series for that...here's the link to buy on amazon.com
http://www.amazon.com/Im-Big-Sister-Joanna-Cole/dp/068814...
if you scroll to the bottom of that page, there are a bunch of books that help with this situation.
as far as things to do to get her involved. you can have her help you shop for the baby. have her help pick out some outfits, some toys, etc. and maybe if the room is big enough, ask her how to rearrange her room to make some more room for her new baby brother/sister (you didn't quite specify which you were having). my friend has 2 kids that are only 1 1/2 yrs apart and her older one used to sit there and talk to her belly, and used to kiss and hug it too. funny thing is sometimes when he's lay right next to her belly and the baby would kick, he'd yell at her to tell the baby to stop kicking him. ah, the sibling rivalry started EARLY lol!
once the baby is born you can ask her to help you get bottles, wipes, diapers...and pick out the outfits. let her help you feed and bathe the baby (my mother had me get her the soap and washcloth and towels, and sit there with her while she would bathe my brother...i was 5). definitely let her hold the baby, just explain to her that the baby is very delicate, and she has to stay on the couch, chair, etc. to hold the baby until they are bigger. NEVER tell her no, you can't hold them, you'll hurt them...just explain why she can't do whatever it is that you're afraid will hurt the baby, and then show her the proper way to do whatever it is. the easiest way to make things worse is to push her away and not involve her...which i understand you're trying to avoid. and until the baby is born, go out and get her a doll...maybe have her pick the doll out. have it be her baby, and show her the things she will be doing with her new sibling once they are born. that SHOULD get her excited to have a sibling.
my mother had me help with everything when my brother was born (except the diapers, i refused to touch him when i could see the umbilical cord...i thought it was so gross! but being able to help with EVERYTHING we got along great...until he turned 2 and started talking and getting me in trouble lol).
i hope that this helps. Good luck, and CONGRATS on the new baby!