Allow the map to be put in a discussion mode in a per user manner. In this mode, think about how people in a conference room can stand up and point at cards while they are talking.. So if a user puts the map in discussion mode, then when they click on cards, the card is highlighted in a toggle fashion and that highlight shows up on the browsers of everyone else logged into the map. So on a conference call, the people can follow along with what the presenter is "pointing at".