These days I steer real clear of '9/11 Truthers' who think the WTC was brought down by explosives and radio controlled jetliners.
I listened to one nutbat at a New Year's Eve party here in SF a couple years ago go on and on to anyone who would listen about Bush's grandfather meeting Hitler on a Nazi zeppelin, the Trilateral Commission, Osama visiting the Bush ranch, timed CIA explosives planted by Marvin Bush, radio controlled jet liners, "Haven't you seen 'Loose Change'? Well, let me get your email so I can... Hey, where are you going?"... Just fascinating. He truly believed it. Really made everyone uncomfortable. He's still out there believing it, I bet.