Introduction
I suppose there are some people in the world with access to the internet or mass media who haven't heard the stories about how the world was going to end on December 21, 2012. The usual reason for picking this date is that a calendar made by the Mayans several centuries ago only runs until this date.
Deeper into topic
Predictions of the end of the world are not new, and there have been thousands of them over the centuries, and they fall roughly into two classes: religious prophecy and weirdness, with the latter including psychics, UFO believers and the truly insane.
John Napier and Jakob Bernoulli predicted the world would end in the late 17th/early 18th centuries — Napier predicted 1688 or 1700, while Bernoulli predicted a comet would wipe out the Earth in 1719. Isaac Newton made the safe prediction of 2000.
Another in the scientist category is Bishop James Ussher, often ridiculed for his estimate of 4004BC for the creation, but he based this on matching Bible stories with independent folk histories and produced the best estimate from the available data.
When Charles Darwin walked past the end of my street in the Blue Mountains on January 17, 1836, and looked out over the Jamison Valley, he assumed that he was looking at a drained seabed. He did not know that the Earth was old enough to allow the "tiny rill of water" to carve out the valley, and it wasn't until about a century later that the discovery of radiation and plate tectonics could explain both the age of the Earth and how the sedimentary rock he stood on managed to get almost a kilometre above sea level. Science is always a work in progress, and it is not fair to judge people harshly for doing the best with what they had at the time.
The outright crazy predictions are the most fun, although they raise a serious question about science education . Nostradamus is there, of course, predicting July 1999. Sheldan Nidle had 16 million spaceships coming in 1996, and Nancy Lieder had the twelfth planet, Nibiru, crashing into Earth in 2003 (both dates since revised to December 21, 2012). Ronald Reagan's psychic adviser Jeane Dixon predicted February 4, 1962, later updated to "2020-2037". Assorted people worried about the Large Hadron Collider in 2010 and Comet Elenin in 2011, with the Earth being sucked into a black hole or shattered into a million pieces.
The different effects it has had
The Mayan prediction was given credence by "Polygamous sect leader Warren Jeffs, Chinese doomsday cult members, and even Australian Prime Minister Julia Gillard" who all "confirmed" the world's imminent demise Even schools in Michigan closed for the holidays early just