1. A method comprising: accessing, using one or more processors associated with one or more computing devices, a social graph comprising a plurality of nodes and a plurality of edges connecting the nodes, wherein each edge between two nodes represents a single degree of separation between the two nodes, the plurality of nodes comprising: a first user node corresponding to a first user associated with an online social network; one or more second user nodes corresponding to one or more second users associated with the online social network, respectively, wherein each of the second user nodes is within a threshold degree of separation from the first user node; and one or more concept nodes corresponding to one or more concepts, respectively; identifying, using the one or more processors, a first set of concept nodes that are connected to one or more of the second user nodes by one or more edges, respectively, wherein each of the concept nodes in the first set of concept nodes corresponds to a multimedia object that is associated with an application accessible by users associated with the online social network; selecting, using the one or more processors, a second set of concept nodes from the first set of concept nodes based at least in part on a number of edges connected to the concept nodes, wherein for each concept node in the second set of concept nodes, each edge connected to the concept node indicates that one of the second users accessed, created, or managed the multimedia object corresponding to the content node with the application; and generating, using the one or more processors, an advertisement of the application for display to the first user, the advertisement comprising a reference to the application and further comprising information representing one or more multimedia objects corresponding to one or more concept nodes, respectively, in the second set of concept nodes.