This study (via the Atlantic) is both pretty clever and hilarious :
METHODOLOGY: To see if conspiracy views were strong enough to lead to inconsistencies, a team of University of Kent psychologists in the U.K. asked 137 college students if Princess Diana was murdered or still alive. In another trial involving the death of Osama bin Laden, the authors asked 102 respondents whether they believed he was already dead when the raid took place or if he was never killed.
RESULTS: The more people thought there “was an official campaign by the intelligence service to assassinate Diana,” the more they also believed that “Diana faked her own death to retreat into isolation.” As for bin Laden, those who believed that he was already dead were also the most likely to agree that he is still living.
Zombie bin Laden!!!