Meh.

Obama: Does a good job with the economy, but is not re-elected by fickle voting public. Maybe Ron Paul? Palin? McCain? Some undiscovered Republican?

Islamic terrorism:

Bin Laden wastes away in a cave somewhere. The cause loses its figurehead and he can't be effectively martyred. The movement starts to die out. Maybe we can expect a last chance attempt at a coup from them which could be potentially deadly.

North Korea:

Either decides to blindly fire on West Coast USA after being told to discontinue its nuclear program, or develops targeting, at which point, they'd be told to stand down. Either way, we get a missile crisis, fairly similar to the one with Cuba (in that we'll want to avoid violence but time restrictions won't be beneficial to politics)

The crazy bastards either stand down due to excellent diplomacy under the gun by the losers at the White House, or fire. Suppose they fire, we target the missile, knock it out of the air, counter-strike, blow Korea off the map.

Don't know what would happen then, I'm assuming there'd be a political freezing-over of Hell because nuking a tiny nation until shit leaks from their microwaved pants doesn't look very good, especially from the US, who already look like warmongers IMO.

Economy:

Maybe a market crash, if not, we certainly get close, at which point, it rebounds and continues its cycle.

Earthquakes:

All of the overdue supermassive earthquakes hit simultaneously, killing us all. (in other words, I don't know and I'm going to leave it in the lap of the gods)

Asteroids:

From what I hear, we can effectively nudge an asteroid such that it misses Earth. I think we're fine.

Solar Shift:

I hope it doesn't release an EMP and fry every circuitboard on the planet.

Pandemic:

Swine flu scares the shit out of me.

Global Warming:

Polar caps melt until salinity is displaced enough to raise the freezing point. Polar caps refreeze and cycle continues. I die and it stops being my problem. Also, Al Gore falls through ice while collecting core samples in Antarctica and freezes to death in the supposedly high ocean temperature. That'll teach the bastard.

Philadelphia:

Phillies, Eagles and Flyers simultaneously win their respective championships.(the Sixers will never win anything, I won't even joke by saying they will) Philadelphia descends into riots and anarchy. By an act of God, a cavern opens up beneath the city, swallowing it forever.

Yeah. That's all I could think of for now.