An internal social network for companies, Yammer lets co-workers share ideas and documents in a real-time message feed. Recently, Yammer launched an updated version of its application with a host of new features. Unlike its predecessor, Yammer 2.0 lets you see who is online and "follow" specific conversation threads to have relevant messages added to your feed. You can use a new poll app to post questions on your feed and view real-time responses. Another app lets you schedule events and track RSVPs. Yammer plans to add a chat feature in the next few months.
COST: Free for the basic service, then $3 or $5 a month per user