This set of recently released 9/11 air traffic/military recordings pretty much puts to rest the entire truther movement in one fell swoop. The surprise attack caused so much confusion between civilian and military controllers and decision-makers that it's impossible they could have all been play acting. Also, a military C-130 pilot witnessed Flight 77 striking the Pentagon, debunking the silly cruise missile theory. One basically has to believe everyone on these tapes was lying to maintain belief in the conspiracy.
Aside from the conspiracy-busting, the tapes are an absolutely chilling reminder of the terror that unfolded that morning, particularly the primal cockpit chaos as United 93 was being taken over. May those terrorist bastards continue to rot in hell.