In one embodiment, a method includes implementing an ad hoc network protocol comprising transmitting, from a first mobile device, one or more neighbor messages that includes a first user identifier corresponding to a first user of the first mobile device, wherein the first user identifier corresponds to a user account of the first user in a social networking system, receiving, at the first mobile device, one or more second neighbor messages from one or more second mobile devices that include second user identifiers corresponding to respective second users of the one or more second mobile devices, wherein the second user identifiers correspond to respective user accounts of one or more second users in the social networking system, and storing, at the first mobile device, information received in the one or more second neighbor messages for access by one or more applications hosted on the first mobile device.