I dont think the earth will stop spinning on December 21, 2012.
Every 26,000 years the Earth's north and south poles shift because of our alignment in the exact centre of our galaxy this event could cause tremendous natural disasters but I'm sure life will continue.The ancient Maya priesthood calculated threw astrology and superstition that this date would mark the end of human consciousness as we know it, not the end of the world. By the way, whats amazing is thier scripture also predicted that the War God Quetzacoatl would have pale skin and a black beard--unknown in that part of the world-- and would return on April, 22nd, 1519 and that is the exact day Hernan Cortes landed on the Central American coast. Whats also interesting is the last time this event happened 26 000 years ago our ancestor Cro Magnon man suddenly began creating great art in the caves of southern France, which to this day remains one of the most inexplicable and remarkable changes in human history.