CorpKnowPedia
CorpKnowPedia, tracking the corporate landscape, attempts to assemble information about which company owns which companies. Operates a MediaWiki installation and content is licensed under GFDL so please support this project get off the ground.
It will hopefully converge with the Research Wiki or at least use enough terms in common that it's automatic to transfer data on ownership lattices from one to another.
Website http://corpknowpedia.org/wiki/index.php/Main_Page
See also: Recyclopedia, Research Wiki pilot