Doomsday.

Trying to distract yourself from something sweet and lovely is difficult. While i was trying to figure out how it could be done i came up with an idea to list all the ways man-kind(woman-kind as well) could end! So here's what my demented brain could think of -

1. A Nuclear Holocaust: Pakistan, which in Chomsky's words is the paradigm example of a failed state, as we all know is a nuclear power. The current political unrest in pakistan is a matter of great concern to all the countries of the world as the extremists and fundamentalists threaten to take over the reigns. No matter how much Gen. Mush claims that he has the situation under control the fact remains that there is a possibility of terrorists usurping power and getting hold of Pakistan's huge nuclear arsenal. Potential targets are USA, India, Israel, Europe. Enough to end man-kind i believe!
2. An Asteroid Impact: An asteroid impact on Earth could have a devastating effect. This theory, made popular by hollywood movies, is as realistic as any other in my list. Earth, moving at a speed of sixty-six thousand miles an hour, goes through an orbit which is criss-crossed my millions of asteroids every year. The number of asteroids which are big enough to completely obliterate human existence runs into thousands but that's not the scariest part - most(read it as almost all) of these asteroids are undetectable. So forget sending a team of drillers to the asteroid and try nuke it, we won't even know until somebody yells 'look, the sun is falling!'. An asteroid of the size of a truck(there are millions of them) could take out an entire city! The chain of events that would unfold after an impact from an asteroid of a football ground's size is unfathomable. It would be wrong to imagine it would only destroy a small region on the planet's surface, the potential aftermath could be breathtaking to hear; first, the asteroid would compress the atmospheric air beneath it and as a result would burn everything in its path even before it touches them!. Second, It would burn/kill/destroy everything that's within a few hundred miles from the site of impact. Third, a flash of blindening light followed by complete darkness. Fourth, my favourite, everything that is within a thousand miles would be flattened out and completely destroyed. This is just the immediate effect of the impact, what follows afterwards is another story. Earthquakes, volcanic eruptions, tsunamis, we are gonna have them all! Half the planet would be on fire and the dust, soot and smoke would block sun for many years disrupting the ecological balance and all the natural cycles essential for life. Mass exodus would lead to utter chaos. Scary!
   
3. Global Warming: Most boring! We have heard enough of global warming in the last one year that it has become so banal to talk about it. But all this hype is not without a reason, global warming sits right in front of us looking straight into our face. It is the only possible catastrophy in my list that could be prevented through collective responsibility. The possible effects of global warming, as wikipedia states, are extreme weather, increased evaporation, destabilization of local climates, glacier retreat, rising sea levels, temperature rise, acidification, shutdown of thermohaline circulation, forest fires and not to mention the drastic effects on world economy. Quite a lot of them, each of which could cause serious damage to the human race. Those who are willing to to do their bit in fighting this monster can visit al gore's site and find out what you can do.
4. An Epidemic: Influenza, cholera, Spanish flu, HIV, Bird flu; History books are full of stories telling about different diseases that plagued humans and caused millions of death at various periods of time. A new virus surfaces each decade causing misery to thousands. Billions of dollars are spent each year on influenza research only to find the virus has mutated and the vaccines have no effect. There is every possibility of a deadly virus cropping up from somewhere and wiping out the entire living population.
   
5. Super Volcanoes & Plate Tectonics: Earth has a history of super volcanic eruptions which have been linked to the mass extinction of certain species. A series of volcanic eruptions around 65 million years ago in India is speculated to be the cause of the most famous paleontology mystery - the disappearance of dinosaurs from the face of Earth. Intense geological activity caused by the friction between tectonic plates could trigger volcanoes and earthquakes leading to mass destruction.
6. Exhaustion of Natural Resources: All the natural resources of the world would get exhausted in the coming few decades with a few a exceptions like the arab world which can boast of huge deposits. Barrel prices would increase making the arabs rich until one day when a fuel-starved country decides to attack them. I would like to think this could set-off of a chain of destructive events, it's my f***in imagination after all.
   
7. Theories from Fiction: I would list some of my favorite theories from books and movies - blood thirsty zombies, created by a biological experiment gone horribly wrong or by alien radiation, alien invasion, devil has a whim to end the world, godzilla rising from the seas, a mad scientist resurrects dinosaurs, robots stop listening to humans and last but not the least, my favourite, a black hole created accidentally by an atom smasher!