The Nutty Roots
This article on 9-11 Deniers more or less takes the tack that "what can you expect when the administration is so secretive and lies so much", but it does have some good bits:
To the extent that there is a unified theory of the nature of the conspiracy, it is based, in part, on the precedent of the Reichstag fire in Germany in the 1930s. The idea is that just as the Nazis staged a fire in the Reichstag in order to frighten the populace and consolidate power, the Bush Administration, military contractors, oil barons and the CIA staged 9/11 so as to provide cause and latitude to pursue its imperial ambitions unfettered by dissent and criticism. But the example of the Reichstag fire itself is instructive. While during and after the war many observers, including officials of the US government, suspected the fire was a Nazi plot, the consensus among historians is that it was, in fact, the product of a lone zealous anarchist.