The Flickr as a Paintbrush post explains how geotagged pictures on Flickr were used to create a map of the predominant colors in a geographic bounding box. The process looks pretty easy, although a bunch of photos have to be downloaded (small sizes should be fine for this, though). I’m thinking of making one of these for Boulder; I’m sure the campus brick would stand out in a similar manner, but I bet there would also be “Flatiron viewing spots” showing up. How to take season into account?