The best way to think about a book talk is to think of it as an advertisement you are giving for a book. You a "talking" up the book and trying to convince others to read it. You will want to convey your excitement and enthusiasm for the book through your presentation, voice inflection and mannerisms.
Watch the video below to find out more. Even though the focus of the video is fiction books, it does provide good general information about how to do book talks.
While what is suggested below is not an exhaustive list of the possibilities of books that could be used for book talks, it is a place to start browsing.