1. A method comprising: identifying, by a processor, information about an entity represented by a first node in a social graph for a social-networking system, wherein the information comprises a location for the entity and an affinity score for the entity with respect to a user, wherein the user is represented by a second node in the social graph; determining, by the processor, that a location of a mobile device associated with the user is within a region associated with the entity, wherein a size of the region is defined based in part on the affinity score for the entity; and executing, by the processor, a special-purpose client application on the mobile device to present, to the user, information related to the entity.