This visualization created by Walter Rafelsberger using Processing shows the conversations of about 1500 users from the microblogging service Twitter. The arcs basically link the locations of users who talk to each other. The geocoding was done filtering location info from the users profile pages and looking it up with Geonames.

via: http://www.visualcomplexity.com/vc/project_details.cfm?id=600&index=600&domain=

and:  http://www.flickr.com/photos/walterra/2631170956/