The list is long and diverse. Would-be censors right, left and center have all challenged books. The urge to stifle thought that we don't agree with is universal; we all have a duty to combat that urge within ourselves.
It is interesting to note that more than "banned" books, we now speak of "challenged" books. These are books that someone is trying to keep us from reading, either by banning or by raising an un-holy stink about them.
The American Library Association's Office for Intellectual Freedom points to this quote from Ray Bradbury (author of Fahrenheit 451):
You don't have to burn books to destroy a culture. Just get people to stop reading them.Thus we see campaigns that complain loudly about certain books. They may or may not call for book-banning, but they all can lead librarians, teachers, parents and readers to shy away from certain books. And that is not good.