A trello like todo tui backed completely with markdown. Out of the box it includes vim-like keybindings that are completely configurable. It's built as a markata plugin.

Markata is a plugins all the way down static site generator that can build your site with nothing more than markdown, but yes is fully customizable at every level. It's designed to come with all the things a good blog should have out of the box such as a sitemap, rss, seo tags, feeds, and code highlighting.