A simple, beautiful Markdown editor using Material Design. View on the Chrome Webstore.
All of the basic commands are explained on every new tab page, which opens by default when you run Markdown, and also whenever you press Ctrl+n, Ctrl+t, or the pink new tab button at the bottom. If you need more advanced formatting, feel free to check out the excellent guide to Markdown syntax by John Gruber: http://daringfireball.net/projects/markdown/syntax.
Version 0.2.2 adds a custom CSS field in the settings menu where you can add your own formatting.
Version 0.2.1 adds a new option in the settings menu to enable syntax highlighting in code blocks. It will automatically detect which programming language you used. Pressing tab when editing now inputs 4 spaces to make typing code easier.
Version 0.2.0 has lots of new options including a settings menu where you can control lots of the formatting and rendering aspects. You can now display equations instantly using LaTeX code (rendered using KaTeX). There are lots more things so check out the Settings tab by pressing Ctrl+K.