I have very little worry about any Mayan prophecies. The Mayans were incredibly advanced in some ways. But they were not prophets or experts in future events. The amazing part about the Mayan calendar was its chronological accuracy, not its ability to predict future events. It was simply math, not prediction of any sort. The were masters of astronomy, and the cyclical patterns of the heavens. Which allowed them to project their calendars into the future thousands of years with astonishing accuracy. But that's very different than predicting any actual events that would/could occur at those future times other than astronomical stuff. Predicting the position or phase of the moon has nothing to do with the world ending by fire and brimstone and raining frogs and rivers of blood.
Also remember that there are many different Mayan calendars. And most of them have already cycled past the supposed end of the world date, due to the invention of leap years in the Gregorian calendar. Some of them won't cycle for many many years after Dec. 2012.