Slack is a rising company in the startup world that is aiming to help other companies and teams be more productive. Their software is perfect for companies that are looking to improve communication within their team. It allows you to create channels so you can easily chat with teammates and is compatible with various other apps such as dropbox, so file-sharing can be made easier as well. Other cool features include universal search as well as a mobile app so you can contact each other on the go.
This San Francisco company has been getting some buzz lately because it has raised a total of $180 million to date. Check out the video that I linked, demonstrating the Slack software and how it works in a team setting.