What is Slack
"Slack brings all your communication together in one place. It's real-time messaging, archiving and search for modern teams."
Basically its a chat application for modern agile software developers :P
Has a great user interface, has all sorts of bots and things to play with, integrates with just about everything and is an all around great tool to collaborate between groups.
Check it out at slack.com and you can even start your own free team. I'd suggest creating one for your family so that you can group discuss or have private rooms. Way better than group chats lol!