At 11:11am on December 21, 2012 our planet will be another 13 Bak'tuns older (or 69k moons*), which you may have heard is the END of the WORLD. Actually it's just the end of the Mayan calender; the last 'birthday' was 3114 BC. Click those links to discover how exact Mayans were with star alignment and physical cycles...
But the most significant fact is that for the first time in 26,000 years (a Great Year) our Sun will pass through the galactic equator of the Milky Way, meaning a great source of energy could be disrupted.
Perhaps a solar flare will simply wipe out all our satellites? Maybe earthquakes, volcanic eruption, giant meteors and tidal flooding? (notice the black Prez... lame duck?)
If you think that's scary, try this on for size: a reverse in magnetic poles - that hasn't happened in 740,000 years (and we're overdue by 240,000 years) Your compass will point South instead of North? Check.
Cataclysmicly devastating events? Check. Laws of physics will vanish? Well, we won't know until then (our magnets will get weaker gradually), but I'm hoping we pass through a Black Hole and we finally get new neighbors, because Mars is so annoying!