I run an office hours chat for my online classes powered by IRC. I use KiwiIRC as the front-end.
Students need only the web address of the web page I want them to go to. When they get there, they need only a username.
No signup, no verification, none of that. They're online, getting help in seconds.
Individual public channels requiring nickserv registration and all that? that's another story.
But seriously - the barrier to entry to get started is this:
https://kiwiirc.com/client/irc.freenode.net/?##irc_can_be_ea...