In this Flash Media Server based tutorial we talk about getting the amount of clients connected to the application and passing that value back to the client that just connected. If you have ever wanted to show the amount of people that are connected to your application then this is the tutorial for you. This is a nice basic tutorial but we do talk about coding for the server side which is still essentially javascript/as1. The client side is built with Flash Builder/Flex in AS3.
Tutorial #44: How to get the amount of clients connected with FMS