Typora - A minimal Markdown reading & writing app.
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.
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
markdown to web - Convert markdown to online web page
Dillinger - joemccann has 95 repositories available. Follow their code on GitHub.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.