In an example embodiment, a message comprising location information indicating a geographic location of a first user device is received. Then environmental information indicating at least one physical environmental condition in the vicinity of the first user device, as detected by an environmental sensor is received. Values representing logical connection strengths between first user of the first user device and other users, the logical connection strengths based, at least partially, on the location information and at least partially on the environmental information, are calculated. Then a second user and a third user to form a group with the first user are determined, based on the values representing the logical connection strengths. A user group is formed containing the first user, the second user, and the third user. Content is received from the first user device and transmitted to users of the user group.