No one knows exactly what will happen on Dec. 21, 2012 -- the day that the Mayan calendar runs out -- but it's safe to say there will be a lot of hype regarding what might happen.

And a lot of people could make big bucks by capitalizing on the folks who are concerned enough about perceived threats, real or imagined, to make a change in their life -- such as Robert Richardson, who runs Off Grid Survival, a website that helps people prepare for worst-case scenarios such as, well, the end of human civilization as we know it.

Richardson's business caters to all sorts of survivalists, but he admits that he's seen increased traffic as the Mayan calendar comes closer to its end date.

"It's going to be a huge year in the preparedness market," Richardson told HuffPost Weird news. "It will be bigger than Y2K."

Richardson doesn't claim to be a full-on 2012 believer, but thinks there may be something to the claims that it will cause a big change on Earth.

"There is something to it," he said. "It's interesting that strange things are converging -- political tensions, weird weather, economic problems -- but it may all be a self-fulfilling prophecy."

On the other hand, some people are making prophecies that they don't believe are self-fulfilling, such as Peter Kling, a 2012 survival advocate and author of "Letter to Earth: You Can Survive Armageddon!"

Kling, whose website calls him "The Einstein of Biblical Prophecies," wants people to understand that nothing is going to happen on Dec. 21, 2012.

"No, it's the end of a cycle. The coldest day of the year isn't the shortest day of the year, it takes time for things to happen," Kling said.

What kind of things? Well, Kling said the end of the Mayan calendar marks the end of a 5,000-year cycle that he claims is associated with big floods. In addition, the date also loosely corresponds with the return of Elenin, a comet that takes thousands of years to orbit and that recently came within 22 million miles of Earth.

The possible effects have been the subject of debate among many 2012 conspiracy theorists -- including Kling -- even though experts like Don Yeomans of NASA's Jet Propulsion Laboratory in Pasadena, Calif., insist that any effects of the comet are minimal at best.

"My subcompact automobile exerts a greater influence on the ocean's tides than comet Elenin ever will," Yeomans said.

Somehow, Kling isn't convinced. "NASA insists it's nothing but an ice ball, but every time it's been aligned with Earth, we've had a major earthquake," Kling said.

Kling points to forecasts on NASA'S website that predict major solar storms next year as evidence that something will be amiss.

To dispel 2012 fear mongering, NASA has set up a page to warn electric companies and other appropriate businesses if such storms get intense enough to affect the power grid.

Still, the Mayan calendar remains fodder for psychics all over the world -- though there are few in agreement as to what it all really means.

"It's not the end of the world, but there will be tsunamis, earthquakes and volcanoes where people don't expect," said Betsy Balaga, a Canadian psychic. "Part of this is because of a pole shift caused by the arrival of a planet Nibiru."

NASA scientists have had to answer questions about the mysterious planet Nibiru for years, only to run into new believers. Their response can be summarized by this explanation from a doomsday FAQ page on their website.

"There is no factual basis for these claims," according to NASA. "If Nibiru or Planet X were real and headed for an encounter with the Earth in 2012, astronomers would have been tracking it for at least the past decade, and it would be visible by now to the naked eye. Obviously, it does not exist."

Balaga sees it differently.

"I believe that the Mayans knew all of this," she said. "I think a lot of ancient knowledge has been ignored."

Since natural disasters seem to be the big fear behind 2012 -- and those, admittedly, are hard to predict -- preparing for the worst makes sense to people like John Kehne, who runs December212012.com, a "clearinghouse" for all the doomsday-related data.

"We do have a shelter here in Louisville that is built for tornadoes just in case anything does happen," Kehne said. "I do think some sort of change is coming. There's been a dramatic increase in the intensity and frequency of earthquakes this year. Based on my records, we've had more intense disasters than any time in memory."

Keith L. Seitter, executive director of the American Meteorological Society, admits it's been an unusual year weather-wise, but bases it on various factors.

"We've had several record-setting events, such as the earthquake on the East Coast, the drought in Texas and the tornadoes earlier this spring, but that's consistent with a warming planet," Seitter said. "in addition, there was a confluence of events on, say, 50-year cycles and 25-year cycles and sometimes those events will happen at the same time."

"However, no legitimate scientist would credit these things to the end of the Mayan calendar," he added.

Meanwhile, if you're unsure of who to believe about how to deal with the end of the Mayan calendar one year from now, you could always do what travel writer Joshua Berman did: ask the Mayans themselves.

Berman is the author of "Maya 2012: A Guide To Celebrations In Mexico, Guatemala, Belize & Honduras," and says there are 10 million Mayans still living in the region and that most of them are not looking at next year as the end of the world, but as the beginning of a cash cow.

"I haven't spoken with a single Mayan or Mayan expert who believes there will be an apocalypse," Berman said. "Instead, there is going to be a lot of celebrating and parties. They hope to increase tourism by 10 percent this year."