Via a posting on this blog, I have come to know about a mind mapping software list. It is "Vic's compendium of software that supports knowledge management and information organisation in graphical form. Includes mind mappers, concept mappers, outliners, hierarchical organisers, KM support and knowledge browsers, 2D and 3D."
The site also includes a new search engine specializing in mind mapping. It is a Google Co-op project built (to minimize irrelevant search results) by manual selection of the web sites from which the results will be drawn. There are 89 at present, listed at http://www.mind-mapping.org/mm_sites.php.
Link to the main site is here