IM-Notify not only allows you to message your predefined groups but, with the appropriate permissions, also allows you to setup topics on the fly with individuals or groups as you desire. When the new topic is setup each topic participant receives a notification of the creation and are able to send messages or other multimedia. These ‘custom’ topics are also fully logged on the IM-Notify servers.
When you’re finished with these topics you can simply remove them to stop any further information transfer.