Map of top 50 mappers by number of changesets (= edits) committed to OpenStreetMap between January 1st 2012 and March 29th 2013. Each yellow dot on the map corresponds to the centerpoint of a single changeset.
This map does not include accounts that are exclusively used for programmatic edits (= bots).
Source for changeset data: OpenStreetMap Planet (changesets-latest.osm.bz2)
Source for aerial imagery: MapBox
OpenStreetMap US – April 17, 2013