You can create your contact lists (address books) and group them into different Contact Groups. You can share files among a contact group or create Group Forum among the group members.
Private Group Forum
Each Contact Group can have a private group Forum, where the group members can participate in special group discussions. The person who created the Contact Group will act as the Group Administrator (he can also assign another member to be the admin)
This feature is very useful for special interest groups, classmates, group of co-workers, etc.
You can also join the discussion board with the public. You must be a "True User" or a "Paid User" to post messages to public forum.