I'm a huge fan of Christopher Hitchens. Here's a list of his articles and essays available online. He's always controversial, argumentative and entertaining, even if you don't agree with what he says.
On the Iraq War.
On an interview given by the Archbishop on Canterbury.
On Burma and China.
I think he also has a back-and-forth written debate with Noam Chomsky on the Iraq war, so I'll see if I can dig it out for you, because they are two of the greatest living writers and intellectuals, and it might be interesting to look at a few articles that directly reference each other.
I also hear that George Orwell has written some of the most influential essays in history, so I'll see if I can pick some of those out for you too.
ETA: Here's a list of links to George Orwell's articles and essays. I haven't read them (yet), but I've heard good things about Notes On Nationalism, and In Defence of P.G. Wodehouse.