I kept a research journal as a blog while I was writing my doctoral thesis. I was teaching Masters students who were writing a thesis themselves at the time, and I was therefore interested in being accountable, authentic, to model learning in public.
In case anyone wants to go back to those distant shores and see what it was really like for me, feel free: http://reasearchdiary.blogspot.com.au
I wouldn’t go there if I were you though, I kind of terrify myself.