A free and open-source reference guide that explains how to use Markdown.

Contains a very nice 'tools' directory with links to multitudes of markdown-compatible tools (especially interesting for people not just wanting to write md on the commandline or in vim but wanting a 'rich-text-like' experience while writing).

A tool doing basically the same job of gnu parallels but with really nice cli interface - simple quoting, reading inputs from file, providing timeouts, retries, multi-line commands, continue flag. Really nice!