We argue that georeferenced social multimedia is really a form of volunteered geographic information. For example, community-contributed images and videos available at websites such as Flickr often indicate the location where they were acquired, and, thus, potentially contain a wealth of information about what-is-where on the surface of the Earth. The challenge is how to extract this information from these complex and noisy data, preferably in an automated fashion. We describe a novel analysis framework termed proximate sensing that makes progress towards this goal by using the visual content of georeferenced ground-level images and videos to extract and map geographically relevant information. We describe several geographic knowledge discovery contexts along with case studies where this new analysis paradigm has the potential to map phenomena not easily observable through other means, if at all.