A beautiful WebGL demo here using the three.js 3D library. Created by Einar Öberg, a Flash developer (and I would also say excellent JavaScript coder!) from Sweden. Einar explains his inspiration and how he made the beanstalk on his blog.
The never-ending beanstalk is actually an audio-visualizer. It’s controlled by the mouse, the music (also created by Einar!) and the momentum of the beanstalk as it grows and sways ever upward. I couldn’t find any giants lurking at the top of the clouds, but do let us know if you find any.
Play with Infinite Beanstalk (requires a browser with WebGL enabled)