Hasn't Aaron Swartz's http://www.jottit.com http://www.jottit.com solved this problem for years now? Go ahead - type in some markdown, then edit the page. You'

Hasn't Aaron Swartz's http://www.jottit.com http://www.jottit.com solved this problem for years now? Go ahead - type in some markdown, then edit the page. You'll be presented with a two-pane view. Your markdown is rendered dynamically. When you're done, just choose the access level for the page (public/private) and you're good to go.