I've been storing all my notes/thoughts/random bits of info for years in Evernote, but started writing primarily in Markdown earlier this year.

While Markdown isn't really anything but plain text with some fancy formatting, Evernote stores notes in it's own proprietary database and has no built in Markdown preview.

Enter Evermark

Evermark is a small program that generates a Markdown preview of the currently selected note in Evernote via Xcode and some Ruby packages and displays the output in your default web browser. While not as nice as something like Brett Terpstra's amazing Marked 2 or a built in MD previewer, it's the best app currently available and gets the job done nicely.