Not a conspiracy theory per se...
But relevent and quite interesting.

Pareidolia is a phenomenon whereby human being tend to see patterns in things where there are none. I've heard it explained in evolutionary terms thus:

If you here a rustle in the jungle and run like fuck because you think it's a cheetah but in fact it isn't, the evolutionary consequence is small, but if you hear a rustle and don't run but it is a cheetah then the consequence is far more severe. the upshot of this is that human have, effectively, been selectively bred to see pasterns in things even when there are none.

I think the majority of supernatural phenomena and conspiracy theories that are not deliberate hoaxes can be explained by this and that the Wikipedia article makes genuinely interesting reading, but then I'm quite dull.

en.wikipedia.org/wiki/Pareidolia

A world full of shadowy cabals and ghosts and gods would be far more fun, I wish more/any of them were true.

Back on topic I quite like the Paul McCartney is dead conspiracy theory. I don't believe it for a second but the intricacies of what is suppose to have happened and all the 'clues' on album covers and such are fascinating.
( CQ Knows the truth, all of it., Fri 2 Dec 2011, 13:29, 9 replies)

See also
The works of Skeptic publisher Michael Shermer.

Yes we're prone to confirmation bias. However, we are meant to also spot patterns for a reason and occasionally there are patterns that are spotted that are genuine. We must bear this in mind before we go entirely the other way.
(Dildo Bugger destroyed a ring on, Fri 2 Dec 2011, 13:31, closed)

While I see your point about actual patterns
I think in the area of conspiracy theory the overwhelming majority are pareidolia pure and simple. All kinds of dodgy shit does indeed go on but it is rarely as coordinated or planned as the tinfoil hat brigade would have us believe and simple co-incidence if often far more likely than it would at first seem.

I tend to apply Occam's Razor if in doubt and I'e yet to see a conspiracy theory that held water, but please feel free to offer examples that do.

Go to sleep B3ta, all is safe, you have nothing to worry about....
( CQ Knows the truth, all of it., Fri 2 Dec 2011, 16:26, closed)

If you read your post...
...standing on your head and squinting, you can see a dolphin.

Proof positive of paradoily, or however it's spelt.
(Harry Webshiter Spiggley biggley bog., Fri 2 Dec 2011, 13:34, closed)

*snigger*
"Paradoily". Just got a mental image of someone jumping out of a plane and pulling the ripcord only to look up and see a parachute full of intricate lacy holes - a paradoily.
( shinyshinyscalp less a man, more a way of life, Fri 2 Dec 2011, 15:06, closed)

Bugger, it was supposed to be a shark
I'll edit accordingly.

How does it look now?
( CQ Knows the truth, all of it., Fri 2 Dec 2011, 16:27, closed)

Jaysus!
You've scared the shite out of me now! I want the dolphin back...
(Harry Webshiter Spiggley biggley bog., Fri 2 Dec 2011, 16:52, closed)

*edits*
There you go, nice and cuddly now.
( CQ Knows the truth, all of it., Fri 2 Dec 2011, 16:59, closed)

one time I played Flowers on the Wall by the Statler Brothers (Pulp Fiction soundtrack) backwards
and I swear I heard it say "Jesus Christ we were stoned last night"
( Moon Girl Technologies horrendous beanbag, Fri 2 Dec 2011, 15:09, closed)

I think this message can be found in most music of the 1970s

( CQ Knows the truth, all of it., Fri 2 Dec 2011, 16:27, closed)