there is a general chat for all users. If you tune into a station a new chat button appears and that's only for people tuned into this station.
many things you can do with dosomething and the station info.
Since it can be html code you can automatic load your website in streamer and with dosomething and a few selfmade scripts you can realize nice features.
By the way i think most users don't want active content served with the audio stream. It's kind of dangerous if you allow to execute code you get with a stream. It can be very dangerous because window is a big security hole you know. There are many buffer overflow bugs.