IRC
Internet Relay Chat is a helpful way to do collaborative development. It's a chat protocol that was already developed in 1988 and that's internationally used for text based communication over the Internet. You can chat with other people on this website in real time at the Special:WebChat page, thanks to the WebChat extension that is part of QualityBox.
For more about IRC, see https://blog.freenode.net/ and http://irc.netsplit.de/