I released another package for GNU Emacs, side-notes. The program simply
displays a side window displaying
side-notes-file in the current directory,
which defaults to
notes.txt. The idea being that you can keep notes for any
project in a simple text file, quickly accessible. The name of the notes file
can be set per-project with a Per-Directory Local Variable or File
Available on MELPA-stable and MELPA.