she likes books, and im assuming brownie points are more useful than something "useful"
whats her favorite book?
i mean really deep down, possibly digging into childhood territory.
figure that out.
then figure out if she owns it.
she doesnt? go find it (more brownie points if it turns out to be rare)
oh, she does own it?
find an autographed copy. (even more brownie points if the author is dead)
if the author is not dead, then get in touch with their agent/publicist and see about requesting a personalized signed copy. this can be done very easily via the internet and email. Offer to either send a book and a postmarked return envelope, or a check for whatever the amount for the cost of the book and shipping.
(or find a signed copy on ebay made out to the same name, she'll never know the difference)
if her favorite is anything by Homer (or similar) then you should really step back and reevaluate the relationship, because if she gets all gooey between the legs for something of that..... intelligence (for lack of a better word, im tired) level then one of two things is is happening here.
1. she is either very very ugly, and that is the reason she is with you, bc shes obviously too smart for you or
2. shes a fucking liar and actually has no idea who Homer is and is trying to seem smart.
EDIT:
also, if she says "twilight"
go buy the hardback edition, of all 3 books in a box.
wrap it up all pretty and write out a beautiful card.
then proceed to repeatedly strike her in the head with it.
hard.
repeatedly.
and then again.