Play back an essay as it's being written
Etherpad is a collaboration app that saves keystrokes as you write. They’ve just added a feature that lets you play back prose as it was written. It’s mesmerizing: you see the sentences burst forth, then shrink down, you see little thoughts emerge into big ideas, you see wild asides whittled down to little footnotes.
This example is venture capitalist Paul Graham’s essay on lessons about start-ups. But the content is incidental; it’s how it’s put down that’s magical.