We recently announced Zoho Chat integration with Zoho Writer, Zoho Sheet and Zoho Mail. This means, if you are collaborating with other users on a document or spreadsheet, you can chat with the other users right within these applications (thanks to Zoho Chat).
If you start a chat session in one application, you can now continue the same chat session across applications in Zoho. This works with Zoho Writer, Sheet and Mail currently. Once chat is integrated into other applications, this feature will flow. Here are few screens of the same chat session in different applications.