It's been known since 2010 that Obama has a "kill list" that he personally reviews to decide which terror suspects should be assassinated via drone strike overseas.
The list is one of the most controversial parts of Obama's presidency, primarily because it's such an obvious instance of presidential power without accountability. But that's set to change – perhaps. The White House is drafting a "Rule Book" that will lay down guidelines and standards for presidential use of the kill list.
Interestingly - or horrifyingly, depending on your point of view - the reason for drafting the rules was not a pure desire for accountability and transparency. No, the motive was Obama's anxiety at leaving the kill list in the hands of President Romney. Per the New York Times, "'there was concern that the levers might no longer be in our hands,' said one official...[and] Obama did not want to leave an 'amorphous' program to his successor."
The Rule Book was set to come out in time for a Romney inauguration in Jan 2013 – but now that's no longer a danger, "the matter may have lost some urgency," as the NYTimes puts it.
As of today, CIA drone strikes have killed 2500 people during Obama's presidency.