Just found the following post by Steve Zeoli:

Using TheBrain as digital bullet journal

Posted on April 12, 2015 by Steve Zeoli

"For the past 14 months or so I’ve been keeping a journal using the bullet journal method, which I wrote about here and here. During this time, I’ve found using a paper notebook quite fun and effective. I’ve been curious about how these same methods could be used with software on a computer and/or iPad. I’ve considered many apps for this, but none seemed to come close to matching the facility of pen and paper. However, I think I’ve finally found an option that could work very well for me.

The following discussion is a bit of a thought experiment on my part, rather than a report on my successful use of TheBrain for bullet journaling. That is, I’ve still only dabbled with TheBrain for this purpose, but I see real promise and wanted to share my thoughts."

Read more at https://welcometosherwood.wordpress.com/2015/04/12/using-thebrain-as-digital-bullet-journal/#comment-2529 -- many interesting ideas here, including "36 Broken Spokes" -- a log of cross country bicycling.