Respectful Insolence pulls from the archives a report on the 9/11 conspiracy theories.
No doubt you've heard of the 9/11 "skeptics" who don't believe that the impact of two large jetliners was enough to bring down the Twin Towers. These and conspiracy theorists like them have been responsible for the movie Loose Change (the producers of which, contrary to their claims that they are doing this "for the victims," have some really vile and despicable things about those who died) and the 9/11 "Truth" movement. These guys love to spin tales about how somehow the U.S. government (sometimes, depending on who's telling the tale, with the help of the Mossad) was actually responsible for the attacks, how supposedly the planes alone were not enough to bring the buildings down, and how there must have been bombs or other devices already in the towers. All of this was done, if you believe the tinfoil hat brigade, for nefarious purposes like giving the government a pretext to invade Iraq, to enrich Haliburton, or a variety of other reasons connected to reality only in the most tenuous way, if even that. One of the more prevalent among the many competing claims (some of which are mutually exclusive) is that it wasn't really commercial jetliners that struck the World Trade Towers and the Pentagon at all, but rather missiles or refueling military tankers. Never mind the thousands of eyewitnesses and the copious photographic, documentary, and physical evidence that do in fact support the conventional idea that it was suicidally murderous Islamic terrorists who hijacked these jetliners and piloted them into these buildings. It must have been the government or the Jews who did it. Popular Mechanics and the most recent episode of Skeptic Magazine have deconstructed the conspiracy theories of the 9/11 "Truth" movement quite well, as has the blog Screw Loose Change and the website Debunking 911, including its claims that the fires in the building couldn't have weakened the steel enough to cause the buildings to fall and that there must have been explosive charges that caused a "controlled implosion."
A report at Skeptic's website can be found here.