In 1979, James S. McDonnell donated $500,000 to Washington University in Missouri for the establishment of the McDonnell Laboratory for Psychical Research. 

When James Randi heard about the project, he offered his services to the project to help avoid the problems Uri Gellar caused at the Stanford Research Institute. Randi's offer of help was disregarded; the researchers insisted they didn't need a magician to assist them in determining the validity of psychic claims.

Two years later, the institute's two chief researchers found what they believed to be two young men who demonstrated--under lab conditions--what the researchers called "psychic abilities." 

Around the same time, Randi held his own press conference with the psychics. He asked them, "Do you cheat?"

And the two men looked at each other and said, "Yes, we do."

The two men were amateur magicians sent by Randi to demonstrate how scientists can be duped by simple slight of hand. They were told, "If anyone asks you 'Are you cheating?' you must say 'Yes.'"

They were never asked.

Nearly thirty years later, both scientists and laymen are still being fooled by charlatains with claims of "psychic" or "divine" powers. Whenever I see books like The Secret or see Benny Hinn on TV, I think of Randi, thirty years ago, proving how easily we can all be fooled... because deep down, we all want to believe.

An intriguing interview with Randi on the subject.
The wikipedia article.