I don't know how those boys and girls at NASA do it but I'll be a nerfherder if they haven't sent a video from the future --December 22, 2012 to be exact-- explaining how the world didn't end on December 21. Clearly NASA's funding hasn't been cut enough if they can still time travel and send online videos from a world that's already been destroyed.
Seriously though watch this video that explains how the Mayan calendar --the one that's got everybody all wound up about the apocalypse-- actually works like the odometer on your fancy automobile and December 21 is merely the day when it flips back to zero. This won't cause the world to end anymore than your car ceases to exist when it flips to "00000." In fact if your car makes it to all zeros on the odometer that's a cause for celebration for you and your mechanic because you've done something wonderful together. NASA are the mechanics of Spaceship Earth. They might get a little frisky with each other every now and then but they don't ever lie to us, the drivers of this thing called life, and now isn't the time for them to start.
So have a look, feel better and realize that it's already December 21, 2012 on this planet. Bruce Willis and Matt Affleck ain't walking through that door, y'all.....because we don't need 'em.