The dark, twisted brainchild of Edmund McMillen and Caulder Bradford.
The very popular Futurama / Matrix crossover series, with amazing 3D Flash!
Sick of stick figure cartoons? Get ready for stick genocide!
When you beat Portal you're treated to this song. It's called "Still Alive" by Jonathan Coulton (http://www.jonathancoult on.com/). Loved it so much I made it into a video. Enjoy!
Edit: Added in music credits. Thanks!