I’ve always liked mind maps for brainstorming difficult concepts.  I find they are a great way of logically expressing, formulating and grouping thoughts that are hard to articulate.

I found mindnode (for mac) does a super quick and super easy job of it!  (And, it’s free).

Here’s one I did for an article I’m writing on identity federation.  (Right-click and ‘view image’ to see it bigger).