Smart mobile phones have become a common sight and every day new uses are found for them beyond their original scope of allowing voice communication between remote peers. Nevertheless, mobility limits the features a smart-phone is able to provide in areas such as storage space and data communication costs. This paper proposes a solution for storing location-aware data in a medium composed of fixed points (workstations), wireless access points and smart-phone applications. The proposed system uses context information (location, neighbors) and techniques specific for opportunistic computing to provide an efficient management of the available data. The paper concentrates on the specific problem of using smart devices to provide a feasible satellite navigation system based on high resolution raster maps. An evaluation of the system's performance is provided based on a custom simulator.