Site Home Page (early iteration - outdated)
These were early design ideas and are now outdated. For current site management wireframes see Group Manager - advanced creation & editing
If the ability to create groups from among site members has been added to a site (is there any reason not to add to all sites?), there will be a Groups menu in the left nav of the site. Under Groups, everyone would see the link to View Groups but a select few would have Manage Groups.