Backchan.nl is a great online tool for creating a back channel chat. This is ideal for presenting in front of large groups for professional development or engaging an audience such as a classroom. Another nice feature of Backchan.nl is the ability to create a poll for voting as well.
I highly recommend giving Backchan.nl a try by clicking here!!
For a much more detailed review check out Richard Byrne's award winning blog.
For other back channel sites click here.