There are several Mayan Calendars: Tzolkin Mayan Calendar, Haab Mayan Calendar, The Mayan Venus Cycle, Mayan Long Count Calendar (The terrorist calendar). In the world there might be hundred ways of dividing time, so finding one with the cycle ending in 2012 was not very difficult.
Furthermore no one was there to check the authenticity of that calendar and given the date of the end of that famous cycle I bet one US dollar banknote it was completely made up by the NOW, they are specialists at designing calendars.
I must remind you that at the time of Jesus of Nasareth the present time calendar, the Gregorian calendar, didn't exist. So Jesus crucifiction was on a Friday, that is it. The Gregorian calendar came to light on February 24th, 1582 after the Jesus of Nasareth's crucifixion and the famous Friday October 13nth, 1307. So as the Order designed the calendar it made it up in such a way that both dates would fall on a Friday 13nth. Never occurred to you that that complicated system of months with 30 days, 31 days and 29 days with 28 days in February had a purpose? Things could have been done in a more simple way, couldn't they?
The only purpose of that Mayan legend was to increase the anxiety of people as they get into 2,012, change what the average opinion expects the average opinion to be and create a Market Crash: In one of the greatest investment markets in the world, namely, New York, the influence of speculation (in the above sense) is enormous. Even outside the field of finance, Americans are apt to be unduly interested in discovering what average opinion believes average opinion to be; and this national weakness finds its nemesis in the stock market.
There are at least one Friday 13th in a year, given the operation of the calendar. One and two are the most common cases. There are three Friday the 13th year if and only if the first day of the year is a Thursday for a non-leap year and a Sunday for a leap year. The next occurrence of that phenomenon will be in 2012 which is a leap year. In that year the Friday 13th will occur on January, April and July. Overall, 13th of the month falls slightly more often on a Friday than any other day of the week. In fact, a Gregorian cycle lasts 400 years and 400 years = 146,097 days (146,000 days plus 97 days, corresponding to February 29). In 400 years, we have a number of weeks on: 146,097 / 7 = 20,871 weeks, where the end of a cycle Gregorian. However, in 400 years, there are 4,800 months, and 4,800 is not divisible by 7, certain days of the week will fall on 13 more often than the others by a calculation (e.g. computer), that day is Friday.
More resources on the projected Crash of 2102 on my Blog.