i did a quick search and found nothing on this topic, but i’m sure sometime it was suggested.
Anyways, Custom Chat Channels are simply Chat Channels that players can create and invite others through either an invitation, password, or publicly open.
to create one you would just type /Channel [Channel Name] [Password]
other commands for changing the password and kicking players would be /Channel Password Change [Channel Name][Password] and /Channel Kick [Channel Name][Player Name]
changing ownership on the channel would be another command as well as keeping it Server Only to prevent spying in WvW.
Chat Channels would be useful for Guild Alliances, Keeping groups of friends in contact, and World vs World Groups.
This system will look very familiar if you have played World of Warcraft.