We have previously mentioned that the Fox X-Files spinoff The Lone Gunmen had become an obsession with conspiracy theorists ever since 9/11. The reason is the pilot episode--which aired a year before the attacks--featured a plot to hijack a 747 and fly it into the World Trade Center.
But if you Google "Simpsons predict 9/11" you find that in a 1997 episode of The Simpsons did the same, in a much more obscure yet creepy manner. In the episode, the family goes to New York. And, while it's not that weird that the Twin Towers would be featured in the episode (Homer's car gets stuck there due to parking tickets)...
http://www.cracked.com/article_18747_5-absurd-but-mind-blowing-pop-culture-conspiracy-theories.html