walkingsf did a series of heatmaps based on flickr data: http://www.flickr.com/photos/walkingsf/sets/72157624209158632/ http://www.flickr.com/photos/walkingsf/s

walkingsf did a series of heatmaps based on flickr data: http://www.flickr.com/photos/walkingsf/sets/72157624209158632/ http://www.flickr.com/photos/walkingsf/sets/7215762420915863...