Smi is a Simple Markup Interpreter / filter for simplified Markup dialect.
smi can be fed text in Markdown, and return HTML output.  smi can be fed
HTML, and return the markup translated to entities.  I use smi as a filter
for devel/cgit to parse the README.md files, returning HTML output.  I am
also using it to markup wiki pages, for a git backed wiki.  The use cases
are limited only by your imagination.