Irc
http://9front.org/extra/rc/ has wcirc and
http://9front.org/extra/src/ has irc7 and ircs
there are probably newer versions of these in sources, or shithub, or other places
http://code.9front.org/hg/irc7/
A few TUI IRC clients like irssi and weechat can easily handle 100s of networks with 1000s of channels.
Imagine for a moment 9 had an irc filesystem, similar to the existing ircfs projects for inferno and for linux. A general purpose tool can be run inside acme to keep track of any changes within a tree hierarchy. All recently written files can be highlighted inside acme, and the most recently updated file can be jumped to, and a tail of the last few lines displayed. This would be a general purpose replacement not just for irssi and weechat, but would be useful for monitoring any type of communications (email, xmpp, matrix) as well as system logs.