Haven't finished Portal 2 yet? Go on and listen to the game's ending tune. Do it.

And those who've already breezed through the game, have another listen.

The song is by Jonathan Coulton and dubbed "Want You Gone". Coulton also wrote "Still Alive", the ending tune for the first Portal.

If you're not familiar with Coulton's work, check out "Code Monkey" and "re: Your Brains".

[Thanks Jimmy!]