First of all, Mou is lightweight and fast. It’s up and running in next to no time. Although aimed at web developers, I think it has something to offer to a wider audience, partly because even without all its Markdown features, it makes a nice general purpose text editor.
But if you are writing in Markdown, those features make it even better. There’s a preview pane in which you can check your Markdown markup – it updates in real time, and can be tweaked to display using a stylesheet of your choice. At the top of the window there’s an unobtrusive live word count, another bonus for writers of all shades.
Mou comes with a selection of color themes, and you can edit your own. I particularly like Mou Night, a dark theme with gorgeous, neon pink highlights. The app is packed with shortcuts and thoughtful extras (including support for opening files from the command line and exporting HTML with or without CSS).
Mou is still in beta, but developer Chen Lou is accepting donations. Anyone who makes a donation will get a free license for version 1.0 when it’s finally released. A recommended download, not just for people who do a lot of writing in Markdown, but for everyone who appreciates a zippy, dependable little text editor.