aka. wagn Peer (merge this stuff there)

freebase
http://www.freebase.com/view/

dabbledb
http://dabbledb.com

info-commons
http://www.maya.com/infocommons/

informl
http://informl.folklogic.net/

semantic wikis & related
http://wiki.ontoworld.org/wiki/Category:Semantic_wiki
http://wiki.ontoworld.org/wiki/Category:Semantic_content_management_system