Markdown New Tab - Write notes in Markdown directly in the 'New Tab' page
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.
NotesHub - Fully cross-platform, markdown based note-taking app
Markdown to PDF - Super simple way to get your markdown files to PDF
UnMarkDocs - Unleash the Power of Markdown to Write Better Product Documentation
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.