If the world doesn't come to an end in 2012, the fearful sheep will have another date to add to a long list of "failed" doomsdays.
195 AD (or CE) deduced by numerology from the Greek spelling of Rome and the Greek value for its letters adding up to 948 which would be the length of time Rome would last.
365 AD (same # as the number of days in a year, must mean something....)
1000 AD Chapter 20 of the book of revelations refers to the 'millenium'
1030 AD possibly the 'millenium' was to be measured from the Passion, rather than the Nativity?
1033 AD (see above)
1492 Sir Thomas Browne noted the belief that (a) the world was created in 5509 BC and that (

its ordained lifetime was 7,000 years. Since he wrote this in 1645, he may have detected a flaw in his calculations.
1496 AD a 'monster' was reportedly fished from the river Tiber, heralding the end of the world....
1524 AD As per the astrologer Stoffler, Saturn, Mars and Jupiter would be together in the sign of Pisces (the fish) signalling a world wide flood.
1588 AD Stoffler tried again, although, no world wide flood occured, the waters DID cover the Spanish Armada.......
1666 AD Ooooh the number of the beast! Kind of, sort of. No end of world, but London was burned in the great fire of that year.
1833 AD William Miller, a doomsayer who bad a career (badly) of predicting the end.
1834 AD Miller strikes (out) again.
1843 AD Miller realized he made an arithmetical error, and this was truly the end year of mankind.
1844 AD Millar tries one last time. At years end, there was no destruction, but a creation: Some of Millers followers splintered away and formed the Seventh Day Adventists.
1847 AD Both the missionary Joseph Wolff and a woman named Harriet Livermore independantly came up with this one, both based upon the book of Daniel.
1874 AD Proclaimed by Charles Taze Russell whose sect would later become Jehovahs Witnesses, the messiah was born, but for reasons of his own would remain under the radar for 40 years.......
1881 AD By "Mother Shipton"
1882 AD by the same Mother.....
1911 AD Charles Piazzi Smyth, Astronomer-Royal of Scotland determined that this date would signal the beginning of the "tribulations" based on "pyramid inches".
1914 AD As per Russell, the messiah would begin now.
I have more, but this is getting long. I'll just give the dates, and if anyone wants futher info, just ask.

1917
1920
1921
1925
1928 (29th of May)
1931
1936
1953
1969
1972
1973
1991
1997
1998
1999
2000
2001
2012
2537
6300
470,000
1,100,000
12,960,000
10,000,000,000 AD According to Encylopedia Britannica, this is when the sun is due to burn out.
Any questions? Oh, the above data was gleaned from numerous books, magazines, and articles regarding the end of the world.