The web lives and dies by the DOM. It is both a beautiful and horrible thing. Here is just one example; it's called "DOM clobbering".
Sometimes referrers reveal sensitive information. Wouldn't it be nice if there was a way to hide them when you needed to?
This is the manuscript for a talk I gave to the GRWebDev. It is the story of a project we canceled at GitHub and the lessons I learned from it.