I don't think any books should be banned. In fact, I hope to one day buy a tote bag that says "I read banned books". One that I've read so far is Fahrenheit 451, and of course, the HP books are consistently challenged in various schools and counties and so forth. I intend to read more of them.
People have the right to publish their ideas, even if I hate them or disagree with them. I mean, there's a book called "The God Delusion" and that really saddens me cuz I'm a christian, but I don't deny the author's freedom to express what he wants.
I also agree with Li Xiang. Banning books brings them more publicity. In fact, if it wasn't for Banned Books Week, I would not have found out about Fahrenheit 451 and even if I had, I might not have been so interested in it.