Wandora

Wandora is a Topic Map editor application. To get an overview of Topic Maps check these:

http://www.wandora.org/wiki/Topic_Maps
http://www.ontopia.net/topicmaps/materials/tao.html
http://en.wikipedia.org/wiki/Topic_maps

However, Wandora uses slightly reduced version of Topics Maps. Most notable differences are described here:

http://www.wandora.org/wiki/Reduced_Topic_Maps

WandoraWiki hosts also topic map conversions of Gellish, WordNet, OpenCyc, Gene Ontology, and Finnish General Upper Ontology (YSO). See links below
http://www.wandora.org/wiki/Topic_map_conversion_of_WordNet
http://www.wandora.org/wiki/Topic_map_conversion_of_Gene_Ontology
http://www.wandora.org/wiki/Topic_map_conversion_of_OpenCyc
http://www.wandora.org/wiki/Topic_Map_conversion_of_YSO
http://www.wandora.org/wiki/Topic_map_conversions_of_Gellish_ontologies