Just finished David Aaronovitch's 'Voodoo Histories', his study of conspiracy theories and why they take root. I actually got a bit bored with the bits explaining why they seem to have a hold on people, but the bits debunking the theories were very entertaining, although, as with 'The God Delusion', I'd guess most of the people likely to read the book are already of a like mind with him anyway. That's certainly true in my case, the only theory I have any time for is the Kennedy assassination, and he makes a very good case for Oswald having acted alone, but he hasn't quite convinced me, to be honest.
Obviously, some are like shooting fish in a barrel - the Diana conspiracy being the most obvious one. I can see why people want to believe in 9/11 conspiracies, though knowing the human race as I do, I'm more inclined to put that down to total incompetence than murderous intent (on the US Government's part). And I have to admit that I had no idea that there were people in the US trying to prove that Obama wasn't born in the US - some people really do have far too much time on their hands.
But I think I'm going to give factual books a break for a while now - I need to read some fiction!