ytalk has to be the best user-interface that I've ever known. It's a multiplayer tmux! We used it to do pair programming remotely around 2003. Your terminal

ytalk has to be the best user-interface that I've ever known. It's a multiplayer tmux! We used it to do pair programming remotely around 2003. Your terminal is divided in two parts, one half for you and the other half for your colleague. You get to see what the other does. It needs no complicated infrastructure: just xterm, ssh and talk.