Anyone who has been paying attention to the news for the past few years has heard of Blackwater USA, a private security company -- mercenaries -- who work as guards, law enforcement officers, and in other paramilitary roles all around the world, often in conjunction with American military forces. A curious phenomenon, so let's learn a little more about them.
Here's a six-part series about the company: "Blackwater: Inside America's Private Army". The articles cover their training programs, their work in Iraq, and their role in the Katrina recovery. Exhaustive and fascinating.
A reporter for Popular Mechanics tags along with Blackwater contractors who ferry VIPs from Baghdad's airport to the Green Zone.
Here's a paranoid sort of conspiracy page about the hundreds of millions of dollars Blackwater is paid by the US government to provide security for diplomats.
Finally, here's the Wikipedia entry for Blackwater USA that contains information on some of their training facilities and business divisions.