Bitrix24 - Bitrix24 is a free (for small businesses) social enterprise platform. It is a united work space which handles the many aspects of daily operations and tasks. Create your own social intranet in minutes!
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
LinkedIn Premium - LinkedIn is a social network helping brands and professionals to connect, identify sales prospects, hire talent, and promote their business.
Salesforce Chatter - Salesforce Chatter provides a suite of collaboration features to any application built on Force.com.
Communifire - Enterprise Social Collaboration Software
XComms - XComms provides desktop alert software tools that allow send out desktop alerts through various flexible messaging channels, reach all employees directly with full desktop targeting, scheduling and real time acknowledgement reporting.