In accordance with one aspect, a client device is sent an indication of one or more types of information available for the client device. In response to the indication, a request is received from the client device to retrieve the information available for the client device. The information is identified and sent to the client device. In accordance with another aspect, one or more friends of the user are identified from persistent data, and a check made as to whether each of them is logged in to the system. For each of them that is logged in to the system, the user is subscribed to the friend's information and the friend is subscribed to the user's information. In accordance with another aspect, a user is allowed to be a friend of another user only if the other user is also a friend of the user.