Guix

Smu is a very simple and minimal markup language. It is designed for using in wiki-like environments. Smu makes it very easy to write your documents on the fly and convert them into HTML. Smu is capable to parse very large documents. As long as you avoid an huge amount of indents it scales just great.

Smu was started as a rewrite of Markdown but became something more lightweight and consistent. The biggest difference between Markdown and smu is that smu doesn't support reference style links.