FCKEditor
From LMD
For WYSIWYG-editing you can use FCKEditor for MediaWiki. It's uses a special version of the FCKeditor WYSIWYG editor that outputs wiki text, not HTML.
By default this addon activated for all users. You can return to standard Wiki-editing through toggle 
icon. Or you can permanently disable it for whole site or for defined namespaces on the "Misc" tab in your Preferences - Rich Editor:* selectors.
