TouchGraph support was removed in Tiki 1.7.9 morcego offers similar functionality but without the user needing to install software on their PC (It is a java applet)
If you would like to get this back working (and can code a little), please contact marclaporte
TouchGraph provides a hands-on way to visualize networks of interrelated information. Networks are rendered as interactive graphs, which lend themselves to a variety of transformations. By engaging their visual image, a user is able to navigate through large networks, and to explore different ways of arranging the network's components on screen.
The touchgraph wiki browser is a nice application that can be used to view a graphical representation of the Tiki wiki.
Please see a TouchGraph WikiBrowser screenshot of tikiwiki.org
TouchGraphDoc
TouchGraphDemo
{WIKIGRAPH(level=>1)}TouchGraph{WIKIGRAPH}