2012 was the end of the Mayan predicted era;
3734 however is when Nostradamus predicted the end. :O
The reason the Mayans probably didn't finish the calendar was because probably around the time they got to the year of 2012, they were invaded by Hernando Cortes and his Spanish
conquistadors and the empire was destroyed.
Either that or they ran out of giant boulders.

Also, yeah the number has been showing up frequently. Even when I'm playing my Steam games, I sometimes see over 100 people with the number 666 in their name in one sitting.