Thanks to Clark Venable's sponsorship, Conversant now has a nearly-complete WYSIWYG editor! You can see it in action here or on Clark's site.
It supports Internet Explorer on Windows, and Mozilla 1.3b+ on any platform. Same features in both browsers.
The HTML editor is a modified version of HTMLArea from InteractiveTools.com, built into a new Conversant plug-in.
At the moment it's only "nearly-complete" because it isn't configurable. Soon it will have a few options for which features to include in the toolbar. When this is done, it will be made available for download (for use with your own Conversant server). Also, it will be built-in to all paid hosting accounts on Free-Conversant.