Not to put a damper on the entertainment value of this thread, but the Mayan calendar is a cyclical one. Just like our calendar starts over on December 31, the Mayan calendar does the same thing only it's cycle is much, much longer. I forget what it was but something like 21 or 25,000 years. If I understand it correctly, it is the time it takes for our sun to orbit the center of our galaxy, just like our year is the time it takes for earth to orbit the sun.
So, essentially the Mayan calendar starts over on December 22.
Some if the facts may be in error but the basic gist of it is here, now back to the more entertaining discussion of the end of the world.
I just looked it up, the full cycle of the Mayan calendar is 7885 years.
Matt