A long time ago in this very galaxy there was a service called Todaysmeet which allowed you to quickly create an online chatroom. These chatrooms were used in classrooms, conferences, and other places. Unfortunately, it was a one person show and the developer was ready to not be on-call 24/7, so Todaysmeet shutdown.
There is still a need for a simple, ad-hoc online chat room, and that is where PALMS Backchannel Chat (also called by the much cooler name YoTeach!) comes in. It has a ton of admin features to make it easier for teachers to create and manage the participants in a room.
They have a video to show off their features: