ZoneTag is a rich mobile client that enables context-aware upload of photographs from cameraphones. In addition to automatically supplying location metadata for each photograph, ZoneTag supports media annotation via context-based tag suggestions. Sources for tag suggestions include past tags from the user, the user’s social network, and the public, as well as names of real world entities such as restaurants, events, and venues near the user’s location. A seamless interface makes it easy to assign tags to a photo, forming the basis for a richer personal media retrieval and organization system. We believe that lowering the barriers to tagging has great potential for effective retrieval.