1. A method, comprising: accessing logical relationship information describing logical relationships among a plurality of users; generating, by a candidate scorer module, scores for each of a plurality of possible groups based at least partially on the logical relationship information; selecting a first group from the plurality of possible groups based on the scores, the first group containing more than one users, including one or more users with whom the user has not directly communicated; adding the first user to the first group of users without causing direct communications between the first user and the one or more users, in the first user group, with whom the user has not directly communicated; receiving content from the first user for broadcast to the first group of users; in response to the receiving of content, regenerating scores for each of the plurality of possible groups based on the content; and adding or removing the first user from a second group of users selected from the plurality of possible groups based on the regenerated scores.