I have added support for footnotes to MultiMarkdown, using the syntax proposed by John Gruber. Note that there is no official support for footnotes yet, so the output format may change, but the input format sounds fairly stable.
To create a footnote, enter something like the following:
Here is some text containing a footnote.[^somesamplefootnote] [^somesamplefootnote]: Here is the text of the footnote itself.
The footnote itself must be at the start of a line, just like links by reference.
And this is what that looks like:
Here is some text containing a footnote.
Here is the text of the footnote itself. ↩