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.
A5 - Takes notes in your browser. Elegant & simple.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.
Falcon for iOS - Writing notes made simple
Markdown New Tab - Write notes in Markdown directly in the 'New Tab' page
Chars - Unicode Symbols Keyboard for iOS