It's growing up team communication platform where you keeping all the eggs in one basket - https://slack.com/
Atlassyn doing hipChat and it suppose to do the same, but I like it way less. And a lot of developers think the same.
It's possible to create a reasonable and free environment using it: bitbucket, trello, google docs, hangout. It would work perfectly fine for the small projects. The only thing that is missing there now - is free bugtracker. It's a whole lot of different integrations, including different bugtrackers but they all not free even for the small startup size projects.