Well, i personally DON'T think the world will end in 2012.
And to be honest, no one ON THIS WORLD will know, only God does. (at least, thats what i believe)
And also, let's say the world was going to end, would we count it down like we do to new years? Would we stay up all night and wait for it to happen? That's just baloney.
And about the meteors crashing thing, it WILL HAPPEN. The earth WILL be struck by a meteor some day, but not any time soon according to astronomers and other scientists. And the world has been predicted to end countless of times and none of them has come true so i don't think I or anyone else has anything to worry about
[EDIT]: The Mayan calendar DOES NOT WHATSOEVER say the world will end. It's just the renewing of a new cycle, aka: The end of the calendar. I mean, our calendar ends every year, and has the world? No.