As I write almost everything in markdown I like to see how it looks. The code editor Coda 2 (strangely) doesn't have support for markdown so I searched for a plug-in to help me out. I found Markdown Wiki Plug-In for Coda 2.
It probably is the next best thing to have native markdown support. In addition to preview it has the ability to generate HTML and you can specify your own style sheet (CSS) to make it look the way you want.