What would be some May 21st Doomsday Scenarios?

Now we have less then a few weeks, world has been acting rather strangely this year...the birds and fish scare, osama bin laden death, the world going to hell in middle east, the japanese earth quake, all this happened and its not even summer yet. If something WERE to happen in a few weeks, what do you think would be a possible scenario for May 21st? Bible sayers believe it might happen and think that the mayan 2012 thing is wrong.