I have recently been looking for a good website to direct people to, who have unfortunately been snickered into buying the conspiracy theories about 9/11. I had previously found a lot of good information out there debunking the ludicrous claims of the conspiracy theorists, but the site below seems to be a good single location where they have been collected together.
As with cults or some religious people, reasons for being invested in these ideas are sometimes more personal and broad than the actual facts. Therefore, deprogramming someone from these ideas can be very challenging. Most of the 9/11 misinformation is intentionally being concocted by people who get off on it, as a power trip or to see how many people they can hoodwink into believing them. If you know someone suffering from their vile efforts, this site can be a good starting point:
If you know of other good sources debunking these conspiracy theories, please leave them in comments, thanks.
(note: links and long arguments for the conspiracy theories themselves will be deleted until or unless I see something new to convince me they aren't nonsense. I'd prefer that I and my websites not contribute to the spread of blatant disinformation and will treat such comments the same as a religious zealot's preaching).