Slack is the main tool we use. It’s awesome. People are criticizing it because they say that it can be distracting, but we love it. It allows us to quickly exchange info with people that are remote.
We also use Pivotal for communication regarding feature requests.
Fizz is our internal tool and it’s a great way to measure your employees’ delivery performance. It works really well for us to know what is going on, and for our employees to get credit for their work and be able to give feedback.
I really like how easy it is to schedule content with Hootsuite. It makes it easy for multiple people to manage the same account. I especially like the browser bar extension that allows you to tweet and share on the spot from any website.