HubPress - A free, open source tool you can use to build a blog using GitHub Pages and AsciiDoc. HubPress is a web application that makes it easy for you to maintain a blog.
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.
GitPress - A blog writing tool based on GitHub, designed for developers
Markdown to PDF - Super simple way to get your markdown files to PDF
Medium - Welcome to Medium, a place to read, write, and interact with the stories that matter most to you.
UnMarkDocs - Unleash the Power of Markdown to Write Better Product Documentation