Banned Books Week takes place this year from September 26 - October 3, and is not a celebration of banning books, but rather a celebration of the freedom to read, and the importance of the First Amendment.
The books featured during Banned Books Week have been the subject of attempted bannings, and illustrate the fact that many people attempt to ban books from a desire to protect everyone else from ideas or images which they find personally distasteful. This is in keeping with Laurence Peters's quote that a censor is "someone who knows more than he thinks you should," and underscores the position of the ALA's Office of Intellectual Freedom (OIF) that "materials should not be excluded because of the origin, background, or views of those contributing to their creation," and likewise "should not be proscribed or removed because of partisan or doctrinal disapproval."
The OIF releases annual lists of the most frequently challenged books, and it's always interesting reading.
Here's a list of the 11 most ironically banned books of all time.
And here's a map that shows that book bannings are a national problem.