Some embodiments of the invention provide an address harvester that harvests addresses from one or more applications executing on a device. Some embodiments use the harvested addresses to facilitate the operation of one or more applications executing on the device. Alternatively, or conjunctively, some embodiments use the harvested addresses to facilitate the operation of one or more applications executing on another device than the one used for harvesting the addresses. In some embodiments, a prediction system uses the harvested addresses to formulate predictions, which it then provides to the same set of applications from which it harvested the addresses in some embodiments.