GitHub Visualizer - Enter user/repo and see the project visually
NotePlan - Make plans inside an individual markdown note for every day in your calendar. Use it as a journal for your daily tasks and plan todos in advance. For Mac, iPhone and iPad.
Codeology - Open-source algorithm that visualizes GitHub projects
markdown to web - Convert markdown to online web page
SyntaxDB - Easily look up programming syntax for multiple languages
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.