I am slowly being converted into a conspiracy zealot on 9/11.
One of the aspects that I could never accept, even from friends who are engineers that I respect, was the collapse profile and time scale of all buildings destroyed in the attack.
The tipping point has been from fellow pilots.
The difference of opinion amongst pilots since 9/11 is nothing new, but the latest from a particular site is becoming rather interesting: http://www.pilotsfor911truth.org/
Have a look. Nothing is impossible if you have enough money to throw at it.