>>9
There is considerable evidence that the hijackers were Arabs. The fact that Israel won the most out of this is so obvious that you needn't even state it. There is some evidence of Mossad agents knowing about the attack and spying on the Arabs, but I wouldn't say it's too good.
But the usual things that truthers claim is so ridiculous that it's almost in line with the main Holocaust story.
What I feel about the issue is described here:
http://dis.4chan.org/read/newpol/1190649699/2