19. A method comprising: storing at a social networking system a social graph comprising a plurality of graph objects interconnected by graph actions, the graph actions having graph action types defined by entities external to, and independent from, the social networking system, where each of the graph actions represent a relationship between two or more graph objects and each of the graph action types define the relationship between the two or more graph objects; providing a music listening interface for display to a second user, the music listening interface including a link associated with a graph action being performed by a first user upon a graph object on an external system; receiving from the second user a selection of the link associated with the graph action being performed by the first user upon the graph object on the external system; responsive to the selection of the link, sending a request to the external system for the second user to perform the graph action being performed by the first user upon the graph object on the external system; and enabling a collaborative music listening interaction with the external system, the collaborative music listening interaction including the first user and the second user synchronously performing the graph action on the graph object; and updating the social graph based on the graph action performed, where the graph action is of a graph action type that was defined by one of the entities external to the social networking system.
19. A method comprising: storing at a social networking system a social graph comprising a plurality of graph objects interconnected by graph actions, the graph actions having graph action types defined by entities external to, and independent from, the social networking system, where each of the graph actions represent a relationship between two or more graph objects and each of the graph action types define the relationship between the two or more graph objects; providing a music listening interface for display to a second user, the music listening interface including a link associated with a graph action being performed by a first user upon a graph object on an external system; receiving from the second user a selection of the link associated with the graph action being performed by the first user upon the graph object on the external system; responsive to the selection of the link, sending a request to the external system for the second user to perform the graph action being performed by the first user upon the graph object on the external system; and enabling a collaborative music listening interaction with the external system, the collaborative music listening interaction including the first user and the second user synchronously performing the graph action on the graph object; and updating the social graph based on the graph action performed, where the graph action is of a graph action type that was defined by one of the entities external to the social networking system. 20. The method of claim 19 , wherein the graph object has a song object type and the graph action has a listen action type.