b - Ban
Will ban the specified user from joining the room. When used by itself with no hostmask it will list the bans that are in a room. Valid hostmasks include nickname!user@host. When a user is banned his ability to speak in the channel is removed. You can use this in events to limit a persons ability to cause problems.
Privilege: Channel Operator status is required to add a ban. User status is required to list bans.
Examples:
/mode #webchat +b
/mode #webchat +b lamer@pm02.digex.net (bans this hostmask)