Map of US built from geo-tags
A research paper (pdf) out of Cornell University, written by David Crandall, Lars Backstrom, Daniel Huttenlocher and Jon Kleinberg, created the above map of the US by using geotagged photos uploaded by Flickr users. As their abstract explains:
Our approach combines content analysis based on text tags and image data with structural analysis based on geospatial data. We use the spatial distribution of where people take photos to define a relational structure between the photos that are taken at popular places. We then study the interplay between this structure and the content, using classification methods for predicting such locations from visual, textual and temporal features of the photos. We find that visual and temporal features improve the ability to estimate the location of a photo, compared to using just textual features.
A great example of how individual user generated content can be contextualized as part of a bigger “picture.”