According to Wikipedia, the following surveys show what others believe happened on September 11, 2001:

1. a Zogby International poll conducted in Aug, 2004 shows 49.3% of New York City residents and 41% of New York citizens “overall” say US Leaders “knew in advance that attacks were planned on or around September 11, 2001, and that they consciously failed to act”.
2. Scripps Howard and Ohio University conducted a poll in July 2006 that concludes “Thirty-six percent of respondents overall said it is “very likely” or “somewhat likely” that federal officials either participated in the attacks on the World Trade Center and the Pentagon or took no action to stop them”, “sixteen percent said it’s “very likely” or “somewhat likely” that the collapse of the twin towers in New York was aided by explosives secretly planted in the two buildings” and “twelve percent suspect the Pentagon was struck by a military cruise missile in 2001 rather than by an airliner captured by terrorists.”
3. Zogby International conducted another poll in May of 2006. This poll indicated that 42% of Americans more likely agree with people who believe that “the US government and its 9/11 Commission concealed or refused to investigate critical evidence that contradicts their official explanation of the September 11th attacks, saying there has been a cover-up.”
4. An Ipsos-Reid poll conducted in September of 2006 found that 22 percent of Canadians believe “the attacks on the United States on September 11, 2001, had nothing to do with Osama Bin Laden and were actually a plot by influential Americans.”
5. An October 2006 New York Times and CBS news poll showed that 28 percent believe members of the Bush Administration are mostly lying about “what they knew prior to September 11th, 2001, about possible terrorist attacks against the United States.”
6. A May 2007 survey of American Muslims released by the Pew Research Center shows that 40 percent of respondents believe that Arabs carried out the 9/11 attacks. Another 28 percent don’t believe it. Among the 28 percent who doubted that Arabs were behind the conspiracy, one-fourth claim the U.S. government was responsible.

What do you believe? Please comment below.

Source: Wikipedia + 9-11 Conspiracy Surveys