Sorry for a non-answer, but I noticed whenever I get excited trying out new tools and apps (I love productivity apps), what is really happening is that I just procrastinate. Tools can be useful but won't make you magically more productive.
Having said that, what I find incredibly useful is Scapple as a form of "smart" paper.
Having said that, what I find incredibly useful is Scapple as a form of "smart" paper.