I suspect that for most people it has the opposite effect, if any.
Sorry, can you expand on that? Are you saying that most people would consider .com to be less cranky than .org? Can you explain that? My gut reaction when I see something that is potentially crank is that a .org is more likely to have multiple people behind it whereas a .com is likely to be whatever some person bought. Moreover, there's a definite tendency for cranks to be a few years behind the times in regards to website design, so the popularity of .com addresses in the late 90s also comes into play.
existential-risk.org
(Updated 2011-12-16 due to a comment by Nick Bostrom.)
'Existential Risk FAQ' by Nick Bostrom
(2011) Version 1.0
Link: pdf html
'Existential Risk Prevention as the Most Important Task for Humanity' by Nick Bostrom
(2011) Working paper (revised)
Link: pdf html