The Rich Text editor will certainly be a valuable feature when all the bugs will have disappeared. Even so, many users prefer to use Wiki Markup. Most wiki software already have a javascript toolbar above the textbox that inserts wiki markup.  It would be a very nice feature to have a (configurable) toolbar, one that either adds more buttons to the existing ones (so far: Insert Image, Insert Link), or a new toolbar altogether.

The javascript and html code is already out there and open source (see dokuwiki and others).  It's just a matter of implementing it.

Example from Dokuwiki: