This is my proposal: http://commons.wikimedia.org/wiki/File:Wikidata_logo_proposal.svg, which is closely related to Wikimedia Commons' logo.

In Commons the red dot (the project) is receiving media files from the different entities surrounding it. I think that we should maintain somehow the same concept: the red dot (the project, the repository) provides data to the circumference (which I understand is a metaphor of "everyone").