MBONE: Multicasting Tomorrow's Internet
The radio free vat often broadcasts music just for people who would like some music playing while they work. Anyone can broadcast music to this event simply by reserving a slot. The information for this is contained in the session advertisement.
You can often see test sessions between various people on the planet. These sessions are created so that one of the parties can test a setup or a tool. Once the testing is done, the parties involved almost invariably start a conversation, begin exchanging whiteboard data, and so on.