http://wiki.axiom-developer.org

Yes, but really what is it good for ? In addition to the usual Zwiki features, MathAction currently supports these mathematical tools:

AXIOM

Axiom is a computer algebra system. It is useful for research and development of mathematical algorithms for which it defines a strongly typed, mathematically correct type hierarchy.

REDUCE

is a general-purpose computer algebra system geared towards the solution of large scale formal problems in mathematics, science and engineering. REDUCE offers a number of powerful operators which often give an immediate answer to a given problem, e.g. solving a linear equation system or computing a determinant (with symbolic entries, of course).

MAXIMA

Maxima is a free computer algebra system, a GPL variant of Macsyma (which was the first comprehensive symbolic mathematics system and one of the earliest expert systems; many of its ideas were later adopted by Mathematica, Maple, and other systems.)

as well as:

Noweb pamphlet format

Supports noweb-style literate programming, generating multi-format documentation and source code from a single wiki page.

LatexWiki
LaTeX? markup in wiki pages, used by the above.
TouchGraph

A java applet for graphical navigation of the wiki.

Now running on this site - see MathActionTests!