Previewing Markdown with Marked.app
While TextBuddy isn’t designed to be a full-fledged Markdown editor, you can use it as such and preview your text using Brett Terpstra‘s wonderful Marked.app. Just choose “Stream to Marked.app” from the “Command” → “Markdown” menu. This will launch Marked (if installed) and display a live preview of your TextBuddy text as you type.