vim-pad - Note-taking extension for Vim text editor.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Gollum - Gollum is a simple wiki system built on top of Git
CherryTree - A hierarchical note taking application, featuring rich text and syntax highlighting, storing data in a single xml or sqlite file.
Trilium Notes - Trilium Notes is a hierarchical note taking application.
Turtl - The secure, collaborative notebook