Sometimes they are part of a campaign or a launch. Other times they are the purpose in itself: an annual convention or a part of a team building event. Many people, variables and disciplines come into play in this type of events, allowing us to learn new things over and over again.
You can see a very good example of this in the launch of Roche's Infinity, where the show included the performance of a mentalist. Another nice example is the "PAC meeting" for Coca Cola Africa with "Sand Art" - a story explained using sand; and lastly, the guerrilla marketing actions for Aigües de Barcelona in the campaign "Stop wipes to the WC".