Markdown is a text-to-HTML conversion tool for web writers, allowing you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid (X)HTML.
Althought I used to prefer Textile for its table support and other niceties, Markdown has won that war and enjoys indisputably wider adoption, as well as making for slightly more readable text when writing essays.
A diagram markup language designed to be embedded into Markdown, used by the SQLite project team
A nice, clean “Linux”:os/Linux editor
A web developer-oriented app.
GitHub’s Markdown flavor in C
A C language implementation of MultiMarkdown
A C implementation.
A very neat terminal presentation tool.
A tool to convert between inline and reference Markdown links.
A markup converter written in Haskell
A Quicklook generator for GitHub Flavored Markdown
|2012||Markdown Service Tools||
A set of OS X system services to manipulate text.
A Cocoa viewer that wraps the PHP renderer.