Can banning a book be a good thing?

My Dad has just read the prologue to Dead Reckoning and wants to ban it! And it got me thinking, can banning a book be a good thing?

I'm taking his reaction as a positive - that I've created a strong emotional reaction with my writing (and he is my Dad, he really isn't going to like the sex scenes!) But what about books that have been banned by people other than family members?

Apartheid South Africa banned a great many books by such authors as Nadine Gordimer, Athol Fugard and all black writers, but the books still found their way in to and around the country - did they become more important and more precious due to their banned status? Did people take more notice of their ideas because they upset the government so much?
What about Spycatcher? Would so many people have read it if it hadn't been banned? Then there's The Satanic Verses- an extreme case, but I'm not sure if I would have even heard of it had it not been for the fatwa. I wanted to understand why words on a page could upset people so much they were willing to kill. Their actions have actually publicised the book and ensured millions of extra readers.

So thanks, Dad, for banning my book - I owe you one!