Zombie Apocolypse, Monetary Default, Worldwide Economic Collapse, Social Chaos, Fire & Brimstone, Tsunamis, Floods, Earthquakes, Tornadoes, Volcanoes, Nuclear Fallout, Polar Shift, Food Shortages, Water Pollution, Mass Starvation, Government Collapse, Congressional Manhunts (I kinda like this one), Tyranny, World Domination, Cosmic Radiation, Solar Flares, Alien Invasion, Comet Collision, Asteroid Impact, Black Hole Envelopment, etc etc etc. If I missed any of your favorites, please add on......