TodaysMeet is a great back channeling site that I found out about from the equally great blog, Educational Technology Guy. After experiencing the use of a back channel chat at the Wisconsin Educational Technology Association (WEMTA) first hand, I really started to love the way it could be used during professional development/presentations.
TodaysMeet is another great site that does this very thing. It will create a private room, that people can chat in, in real time, and even bring in posts from Twitter via a hashtag.
I highly recommend checking out TodaysMeet by clicking here.