TodaysMeet shut down. Since then I have been using Backchannel Chat to create backchannel chat rooms. While it isn't exactly like TodaysMeet, it is probably best alternative that I have used in the last two months.
On Backchannel Chat you can create a free backchannel room (AKA chat room) in which you can post comments and questions for your students to respond to. Your students can respond in realtime. Students can ask you and their classmates questions within the confines of your Backchannel Chat room. Watch my video that is embedded below to see how you can use Backchannel Chat.