What are topicmaps?
A topicmap is, in general, the popular name for a way of thinking, and two open standards; the XML-based standard named XTM, and the ISO 13250 standard named HyTM.
Other much used topicmap links
TopicMaps.org - Where the standard lives.
TopicMaps.net - An informative web site about Topic Maps.
TopicMap.com - Hand-crafted Machine-generated Knowledge Interchange.
EasyTopicMaps - A WikiWiki about topicmaps.
CoverPages topicmaps - XML/XTM Technology Reports.
Mojix.org - A Japanese website with a topicmap sub-category.