Stumbleupon but for knowledge — this could actually work. You stumble knowledge of particular subjects instead of blog posts and comics. Very interesting. Cool idea, lots of fun I've been generating ideas for 20 minutes now.
A side project of mine is sort of a stumbleupon for knowledge. Sort of. It's more like a directed stumbleupon; you get web pages related to the page you're currently on. Good for research, but knowledge-stumbling works too: http://jellly.com
