Groups are a great shortcut when you want to frequently send baloonrs to the same people.
You can create a new group by going to the Groups tab in the top navigation, and then clicking on the 'Create New Group' button. You have to provide a group name and specify whether you want this group to be private or not. Private groups are only visible to their members and can only be joined by invitation.
Once the group is saved, you can add/remove group members and assign group admins by clicking "Manage" in the Groups list:
You can then add members using a comma-separated list: