Yep, I agree with Jareth's earlier post with his 4 points. However, do you actually know why the mayan calender ends? It is because their solar calculations can no longer function. We pass a "midpoint" in our galaxy changing the position of many celestial bodies. The worst that can happen is a magnetic pole switch.
ok i believe something will happen in 2012 i was thinking that you see all these alein movies that they come to earth and try to destroy us well i think maybe something like that will happen cuz i dont beleive that if an alien will come to earth that it will be greeted nicely. humans will start a war with them if they come.