This entire website is based on my own version of this kind of obsessive note taking.
Did you know that?
My note taking strategies are centered around categorizing ideas and quotes.
I mostly use Evernote (sign up here).
But the goal is to index ideas, and seeing how those ideas overlap as my archive grows.
For example: You would be astounded by how many successful people are saying the same things.
I mean, simply in regard to the link above, here are 5 more examples: