@Lerts: Sometimes we recognise something because we want to see it, because in actuality humans look at the world in a very simple way with very simple iconography and that means that we can recognise those simple patterns when they reoccur.
Like a bush shaped like the head of Jesus, is a round topped shape bush with a few darker breaks in the leaf pattern underneath just a coincidence, or a sign of the second coming? Well, what other personalities from history could be seen if you stared at the same shape? A few roman emporers maybe, some bloke from down the street, and it also might look a little bit like the bins we used to have at railway stations years ago.
We have such a simple view of the world and the iconography that makes up our history and popular culture that we tend to see that which we relate too, rather than that which is there. We can build a conspiracy theory into anything just because we want there to be one, and where would we be without a good doomsday to fear? I've lived through lots of doomsdays already, the exact quantity is hard to tell without immediate access to a Jehova's Witness, but quite a lot.
The 21st December is no different, except people close to me genuinely fear it, as have people throughout history. So which one of these nay sayers was first, the date has travelled through history with it's own subcontinous, and re-ocurred, because people want to believe it's the end.
We know the Mayans where expert astronomers, we know they did calculations of astrological bodies and their orbits and what have you far more accurately than we do! They saw the planetary alignment with the milky way and then what...
Well they said it was the end, was this because of an earlier religious belief of their culture? Had they just got to the limits of their science and didn't know what would happen after? Did they have a conflict of their own between religion and science as we have today? Maybe the people who made the calender knew what happened next but didnt want to publish it for fear of religious persecution?
We see a doomsday scenario because that's what we want to see. But in reality, aren't we just echoing an old myth because we don't have the information we need to know any better?