We're Doomed! (Part 1)

It's the stereotypical post-WWII sci-fi story. The human race is wiped out by an atomic war. The sole survivors are an American astronaut and a Soviet cosmonaut, both in orbit in their separate spaceships. Diminishing oxygen supplies force them both to land on some remote tropical island that's the only place untouched by the war, and as the American climbs out of his ship, .45 in hand, he thinks, "Well at least the last man on Earth will be U.S. Air Force Major Adam Adamski!" He takes careful aim at the Russian, but in that last moment of hesitation before he pulls the trigger, she removes her space helmet, to reveal that she is a stunningly beautiful blonde, and says in thickly accented English, "My name is Captain Eva Evanovitch. I want to make babies and repopulate the Earth."

He says, "Too bad, I'm gay," and shoots her anyway.

Just kidding!

But seriously; the field of sci-fi is simply cluttered with end-of-the-world Adam & Eve stories. Every writer has written at least one; even Jules Verne's last known story was "The Eternal Adam." For some reason we in the field of sci-fi simply love to destroy the world, and then offer humanity a hope for a fresh start. (Except for Nevil Shute, who destroyed the world and then offered absolutely no hope, which is why no one is talking about doing a big-budget remake of "On the Beach" at the moment.)

I'm not interested in exploring the pathology of Jeremiads; that's a topic for another time. Instead, I want to put forth this question: what is your favorite end-of-the-world complete-destruction-of-humanity story? Right now it's a toss-up between Greg Bear's The Forge of God and Douglas Adams' Hitchhiker's Guide to the Galaxy, but I'm open to suggestions.

What's your nominee, and why?