MultiMarkdown, or MMD, is a tool to help turn minimally marked-up plain text
into well formatted documents, including HTML, PDF (by way of LaTeX),
OPML, or OpenDocument (specifically, Flat OpenDocument or ‘.fodt’, which
can in turn be converted into RTF, Microsoft Word, or virtually any other
word-processing format).
MMD is a superset of the Markdown syntax, originally created by John Gruber.
It adds multiple syntax features (tables, footnotes, and citations, to name a
few), in addition to the various output formats listed above (Markdown only
creates HTML). Additionally, it builds in “smart” typography for various
languages (proper left- and right-sided quotes, for example).