I second this. Tiddlywiki has this kind of nesting support which makes it ideal for brainstorming, note taking, etc. The structure is extremely flexible, you ca

I second this. Tiddlywiki has this kind of nesting support which makes it ideal for brainstorming, note taking, etc. The structure is extremely flexible, you can structure your notes however you like. A similar old OSX app.was Voodoopad. Not sure if its still under dev.