Just a note that ConceptMap.io now uses Visjs instead of D3js as its graph drawing library, primarily for displaying thumbnail images from Wikipedia and Wikidata. Attached is a sample image of a concept map whose subject is Q42 (Douglas Adams), and you can view/edit the live map by clicking this link: http://bit.ly/1NlbpRi

Thanks for your help and feedback for this update.

Regards, James Weaver