On the Server you can currently see active devices on the dashboard, and consequently which users are watching what on what media.
However, there's no way to abort these active devices to either conserve bandwidth, conserve server CPU, or simply to stop a renegade process.
One use case that would be particularly helpful is when you're casting from the phone app to ChromeCast. If the phone gets interrupted, you lose control over the stream so that the TV stops showing whatever you were watching, and there's no way to stop it or regain control over it.
Instead of having to stop and start the entire server, it would be nice to just click on that particular activity on the dashboard and press KILL (or perhaps a less dramatic word - cancel?)
Food for thought?