It's a strange thing, so many apps competing to be the "quietest" writing space. QuietWrite might have a shot at the title, though. It's just your auto-saved text, a menu (if you move the cursor), and public publishing, if you want it.
There is, in the settings, a place to change your chosen font, font size, and the name you publish under. But beyond that, QuietWrite is a plain, blue-themed place to do some writing. The publish-if-you-wanna model is novel, and gives you a place to direct a group or just friends to your writing that's not quite as public as a blog post.
QuietWrite is a free webapp that requires a sign-up if you want to publish a number of posts under a common name.