Shows your Mumble server's channels and who's connected. It also displays status icons (i.e. if a user is muted or deafened).
The Mumble Channel Viewer will display all of the channels in your Mumble server, as well as who is in those channels, and their current status (i.e. registered, muted, deafened, etc).
This widget communicates with your Mumble server using the Channel Viewer Protocol (CVP). If you host your own Mumble server you can implement the CVP using MumPI. You can find a service provider that implements the CVP on this list.