I will add some small (and rather hackish) scripts for my personal use here.

footnotes will convert footnotes in MultiMarkDown format to the format of the Wordpress plugin footnotes and back.

Usage: footnotes --to mmd|wp [--file $inputfile]

mmm (MIME multipart/alternative from Markdown) can create a MIME multipart/alternative mail, containing a text/plain part (in Markdown) and a text/html part, from a Markdown file. Other mail headers (From:, To:, Subject:, ...) can be prepended from a template file.

Usage: mmm [--file $inputfile] [--headers $templatefile]