Prose, a content editor for GitHub, optimized for managing websites, to get a web based interface for managing your Jekyll site (or other text-based content in your Github repositories). You can now write a new blog post or fix that typo without even leaving the browser. You can even specify metadata defaults for your posts.
This work really out of the box if you host your site on Github via Github pages but if you, like me, are using Heroku you need to set up some more automation. See my previous post on how to automatically deploy to Heroku when pushing to Github.