A wiki in which every page can define an object:

* a wiki object can iterate over two inherent collections - its contents and its backlinks
* a wiki object's class is defined by the categories it links to
* each category defines a set of methods that extend the view/edit/link/delink semantics of a wiki object

Anyone built one of these critters? --PeterMerel

''I believe that http://www.flexwiki.com/ - listed on the page TipsForWardAtMicrosoft - is somewhat programmable.  I don't know if it meets your full criteria.''

It doesn't. But VistaSmalltalk in its "code wiki" incarnation seems pretty close ... see http://vistasmalltalk.wordpress.com/page/3/ for a sketch ...