WriteNext - The writing application that boosts your writing. Increase focus and writing performance and reduce distractions by separating your creative writing from other activities. Let writing be the only activity you perform in the writing application.
Tomboy - Apps/Tomboy - GNOME Wiki!
Writebox - Writebox is a simple and distraction-free text editor for Chrome and iPhone/iPad.
Turtl - The secure, collaborative notebook
Calmly Writer - Distraction-free text editor for Mac, Windows, Linux and ChromeOS.
Omni Notes - Note taking open-source application aimed to have both a simple interface but keeping smart behavior