There's a very good video on 9-11 that highlights some inconsistancies in the attacks. The ones that had the biggest impact on me were the testimonies in which those questioned reported hearing bombs going off, flashes occuring after the planes hit the towers (indicating explosives, as the fuelages haven't hit yet), and the fact that the video of the "plane" hitting the pentagon has the wrong date.
There's a ton of info in it.
Of course, the attacks could always have been staged in an attempt to stir nationalism and justify the expansion of the police state, but I doubt you guys would buy that.