Just in case this is of any interest to people here -- I recently started using a text editor called HippoEDIT (http://www.hippoedit.com/ -- bad name, good editor). I put together a Markdown syntax file for it (http://www.hippoedit.com/syntax_details.php?syntax=mmd). It includes one or two elements of MultiMarkdown as well, including tables. Inline HTML is also highlighted. For the record, I'm not part of the HippoEDIT team, (although in the interests of full disclosure, I should also add that the HippoEDIT developer did give me a free licence for supplying the syntax file).