So I've had this thought to, and I think you should try it. Because if you are like me, you'll find that most sites have no content worth taking notes on. I set the bar even lower, just try to have the site give you an idea, any idea, but most sites couldn't even do that.
although I had another thought; when I browse the web, my brain switches from creator mode to consumer mode, and in consumer mode it's a lot harder to come up with ideas.