On irc you can message any one person directly. You can block all other incoming messages. You don't have to join any rooms. Or you can make your own room and make it mode +i (invite only). Nobody can join unless you invite them. Or mode +k (nobody can join unless they know a key word.) I have been on irc forever, so if you want any help with it, I'll be glad to confuse you further. licq is another possibility, linux icq. I haaven't tried that yet though. I use braille, and irc does everything i need. and theres the old talk or ytalk or ntalk program. some version of that is in linux. It still works with some isps.