I have been developing features since 2003 in a new area called Collective Control where multiple people control the same cursor to accomplish tasks. There are excellent features you can make with collective control but more on that later perhaps. The Flash Media Server is ideal for collective control because it gives you what is called a shared remote object. You can share the position of a ball on the stage, for instance, and anybody looking at the application can move the ball and the others will magically see it move on their screens!
But what if you want to show other people your ball moving but do not want them to be able to move your ball themselves? And each other person might want to move a ball of their own but not let others move it. Or if you don’t want to share the same text field but rather have your own chat box. This is the traditional multi-user game scenario or a chat scenario, etc. You can do this with the Flash Media Server as well but it requires server side ActionScript and can get fairly complicated.
So I developed a Unique Control class and supporting server side ActionScript that lets you handle this all from within your regular client side ActionScript. It still gets conceptually tricky but it is actually quite elegant and has helped a number of students quickly complete chats, video conferencing applications where each gets a streaming video which can be moved around, and shared drawing applications, etc.