Flickr is a website on which to post photos. The basic services (host your own page, post images, post captions and tags, get comments, notify groups of posted images, etc.) are free. Mappr takes Flickr one step further. By examining the tags, Mappr "geocodes" images on a US map. (There's a bit of Canada and some big cities, too, according to the docs.) Of particular interest to me was the "level of confidence" noted for each image. An image with Red Rocks, concert, etc. yielded a complete confidence of it being in Morrison, Colorado. A photo of a church with minimalist info "Arch detail of a York church" provided low confidence it was in York, PA. The general methodology of geocoding is documented here.

Unlike the very smart document version of this technology from MetaCarta, this service is interesting because of its open, free form coding and its openness to the public. Flickr is free and Mappr has been free and available to the public since January 10.