1. A computer-implemented method for facilitating a conversation amongst a plurality of user devices communicating over a digital communication network, the method comprising: receiving a request to initiate a conversation from a user device associated with an opening user, the request comprising substantive content provided by the opening user and designation of one or more users or user groups as being members of the conversation, at least some of the conversation members being explicitly authorized by the opening user to subsequently designate additional users as members of that specific conversation; receiving a request to view at least some portion of the conversation from a querying user device; determining whether the querying user device is associated with an authorized conversation member; if the querying user device is associated with an authorized conversation member, publishing to the querying user device an authorized member conversation view for rendering on a display screen of the querying user device, the authorized member conversation view comprising conversation substantive content and a user interface element enabling a user to add a new member to the conversation; and if the querying user device is not associated with an authorized conversation member, publishing to the querying user device an unauthorized conversation view for rendering on a display screen of the querying user device, the unauthorized conversation view precluding a user from adding a new member to the conversation.