My apologies to the vim contingent for dragging emacs out into the light again, but it’s pertinent and it starts with the letter J: jabber.el.
In AUR as emacs-jabber, this implants a jabber-based messaging client inside emacs. Good grief, is there anything emacs doesn’t do?! 😉
By most accounts this has been around for a while and I had only moderate difficulty setting it up; the instructions for 0.7.90 on this wiki were very helpful. Without them, jabber.el could never connect to the Talk server. 😕
Beyond that, as you can see, I didn’t do much to add contacts. Mostly because I wanted to see if I could spawn a black hole by telling emacs-jabber to connect to myself.
No such luck. I guess emacs doesn’t do everything … yet. 😯 🙄