I did a bit more looking and found a couple of very interesting options, web.py and Bottle.
I started looking at Django (http://www.djangoproject.com) a few years ago and even did one internal application using it.
The usual complaint about Wikis is that the syntax gets in the way. That is, you have to insert syntax (which is usually somewhat different in each Wiki) to get things done. Well, Zim has no syntax or, more accurately, you don't work with it or ever see it. Zim just uses it internally to offer the functionality. While you can't really call it a WYSIWYG, it's close and you don't have to do funny stuff to get the WYSIWYG features.
Did you ever use Wordstar or PCWrite?