In my own opinion...
I. While the planets are lined up there will be a gravitational pull on the sun that will cause a solar prominence.
A. The solar promince will burn us
B. It will cause Electromagnetic problems for the plane
C. It will release anti matter(which is real and produced by the sun)
1. The anti matter will destroy the planet or a part of it
II. While the planets are lined up there will be a gravitational pull.
A. This gravitational pull will move our moon a little bit further away so that it will be lost from our orbit
1. This will be bad but I don't remember why
III. Something Supernatural
A. Aliens
1. We will learn how sardona was made on the red planet
2. They will explain stonehenge to us
B. Where ever the mayans went to we will go
1. aliens once more
2. portal or rift to another dimension
These are my thoughts about 2012. Although i also think that a world ending is not as bad as we make it to be. Like the end of a gaming world. (Tabula Rasa)
http://www.gamasutra.com/php-bin/news_index.php?story=22528Or then end of the world because of a giant EMP. Did you know that a nuclear blast in outer space will spread an EMP wave that will disrupt the electronics below. Also it will spread further then if it was blown on the surface of the planet.
Or maybe a country by something like.... a country or continent being overtaken by water. Thus ending their world.... who knows,
but remember that global destruction is not the only way to end someones world because your world is relative to your views.