For the non-linear plotter

Maybe try mind-mapping

This is TOTAL RECALL, a mindmapping app (free) on the iPhone-wish the developer would do one for Android.  I'd prefer doing it on the Galaxy tab, but none of them work as well as I'd like.  So this does the trick, for now.

The other mindmaps available for Android may suit you well enough.

How to use it?  Well, that's up to you.  You create a map.  I like it better because I see my book in a short series of ideas and I connect them, so to speak-an image like this lets me do it. Much easier than typical plotting methods.