Google+ Comments is a system plugin for Joomla 2.5 and 3.0 which not only enables visitors to comment on your Joomla content promptly, but also increases your web traffic.
Google+ Comments allows users to share comment on Google+ in public or specified circles as well as disable replies and lock comments. Then Google+ users might click on the link and come to visit your website. If you provide a Google+ Profile ID, you will be able to moderate the comments.
Google+ Comments uses social advanced features to manage comments. Visitors on Joomla sites can reply or give +1 to comments of other users directly in the comments box.