The HMath project (http://jsurfer.hartlage.de/hmath) 
aims to create a MathMl-enabled engine for a Wiki/Weblog.

Displaying MathML requires
* a recent version of Mozilla or Netscape.
* Internet Explorer (version 5.5 or greater) + Mathplayer plugin available from Design Science: http://www.dessci.com/en/products/mathplayer
* under Opera (and probably Safari) the math expressions will be renderer with cascading style sheets.

The input is based on TeX expressions.
To get a first impression see the TeX Sandbox:
http://www.hartlage.de:8080/hmath/space/TeX+Sandbox

HMath is based on SnipSnap, an open source Wiki and Weblog package.

You can find the development page here:
http://www.sourceforge.net/projects/hmath 
----
''This delivers the following error to me:''

 XML parsing error

 fatal parsing error: the document is not in the correct file format in line 83, column 6
   <tr><td align="left" valign="top" class="page-portlet-1">
      ^
''In case it's relevant I'm using Konqueror 3.0.4 on KDE 3.0.3.''

This problem should be solved. Unfortunately I have no Konqueror available -- KlausHartlage