Emacs (and hence Emacspeak) has an extension for writing and manipulating markdown files. I use markdown for writing the posts and pages for this site and others.
Nikola can be used with a number of different document compilers, that is, programs or plugins that can take documents authored in one kind of plain-text mark-up and convert it to another.
One of the best of these is markdown. Using markdown it is possible to write realy quite complex content, without the need to add the HTML or other complex mark-up tags that can make it difficult to see the wood for the trees.
Emacs has a major-mode for handling these files. I have published a page that contains tables of all the Emacs key-bindings for markdown-mode.