Fark linked up this New York Post editorial which nicely summarizes why anyone who believes 9/11 was a giant conspiracy is a complete and utter loon.
Not like that'll stop any of them. If proof was all that it took to debunk popular myths then JFK would've been killed by one nut with a rifle long ago. Elvis would be quite dead and buried in his tacky back yard. Bigfoot would be a tall guy in a costume. The Loch Ness monster would be a wooden cutout in a lake.
Well, except for oil prices. Those really are controlled by an industrial/Republican cabal who have quarterly meetings with Carl Rove in the Willard to make sure the elephants stay in power.