MindMap allows to display in a graphical way the connection among wiki pages in the tiki site. It does not allow the design of new mindmaps (creating the required pages at the proper places), but just the display of previously created and linked wiki pages.
Point your browser to tiki-mindmap.php and a map or your wiki will be displayed, using the relationships between the wiki pages in your Tiki. Think Backlinks!
MindMap feature needs to be enabled under "Admin home > Features > Experimental > Need Polish > MindMap"
Moreover, since Freemind is licensed under the GPL and Tiki under the license LGPL, you need to install one file separately. The instructions will appear if it has not yet been done.
PluginMindmap aka Freemind viewer allows to generate a drawing illustrating connected ideas in a graphical way, previously generated with "Freemind" mind map generator