It has now been revealed that, while mayor of Wasilla, Sarah Palin was interested in having some unspecified books removed from the Wasilla library. She mentioned this at at least one city council meeting and broached the subject with the librarian, Mary Ellen Baker, balked. Palin later gave Baker a letter of dismissal, for not fulling supporting her as mayor, but retracted it when the community rallied to support the librarian. The matter went no further and no books were removed or banned from the library.
There is no indication in any story I’ve seen about just what books, authors, or topics Palin was thinking about banning. Time‘s story on it just says that some voters apparently thought that some books had inappropriate language.
The American Library Association keeps track of challenges to books. Here is a list of the 10 most frequently challenged books between 2000-2005 and here are the 100 most challenged between1990-2000. It’d only be a guess, but it seems likely that the books that Palin was concerned with would be on these lists; most of the books in question were challenged by people with a socially conservative point of view, as opposed to a more liberal one. Wikipedia also has a list of frequently challenged books, many of which link to articles about the books in question.