1) This is popular knowledge already, but for those who don't know, the Mayan calander runs out on December 21st, 2012. Now, the Mayan were an ancient and complex civilization lving just north of the Aztecs, and they did predict alot of events that happened after their empire was destroyed. They think it's not the end of everything, but the start of a "new age".
2) The Sun. Some of you may know that it follows an 11 year cycle of activity - going from huge bursts of activity to quietning down and back again in 11 years. Since 1940, for no reason at all, it's been rising in activity and releasing hge bursts of solar flares and the like, which can prove dangerous to the Earth. Some of you may remember the Canada blackout a few years back. 2005 was a "solar minimum" year, but actually saw the Sun literally exploding with activity which "may" have caused the super hurricane season that year, including Katrina. If the Sun can do that at minimum, think what it could do at maximum, which is, oh look, in 2012!
3) Storms here on Earth are related to the Suns activity. So with huge solar flares, comes sooped-up huricanes here. Maybe twice the destructive power of Katrina.
4) Something you may have heard about is that the Earth's magnetic field is losing strength, due to an imminent reversal in the field. This is perfectly natural, it happens every few hundred thousand years or so, but for about a hundred years or so, the Earth will have no protection from the Sun's radiation. At all. Cracks are already appearing in the field...
5) Russian geophysicists believe that the Solar System itself is entering a huge interstellar "energy cloud". They think this could be the reason why the Sun has gone haywire, and it could have un-told consequences on the planets too. Probable time-frame when we fully enter the cloud? 2010-2020.
6) The Earth almost always goes through a huge extinction event every 65 million years. Physicists are now 99% sure that we are now overdue for the next one...
7) The Yellowstone super-volcano is poised to erupt with positivly nasty consequences for North America and the world at large. The last super-eruption wiped out 90% of the human population 74,000 years ago.

9) The Middle-East. The triparite religions of Christian, Jew and Muslims are preparing for Armegeddon, with many planning to cause it. Israel especially is the one place to watch. Who knows? Maybe the Apocalypse is the one event that human beings have the power to prevent.
10) Have a nice day.