I often hear from readers asking for an easy way to jump between markdown and Microsoft Word. It's never really been that easy. The most recent version of iA Writer takes a lot of work out of this problem. They have built in a converter that goes between docx files (Microsoft Word 2007 or later) and markdown. You can drag and drop the word file on the icon and it opens as a markdown file. Conversely you can export a markdown file from inside the application to docx.
Obviously there will be problems if you bring in multi column documents with advanced formatting outside the bounds of markdown. I tested it with a complicated document and it imported just fine but it did strip out some of the advanced formatting.
There's a lot to like about iA Writer and I'm glad to see they're continuing to innovate.