Let the developer and user decide whether the new item menu will go as submenu under "plugins"
or
The new item menu will be created in the admin main menu bar

In the plugin set the new boolean 


public bool AddToPluginsMenu()
{
            return true;
}


this can be set by the user from the configuration window by adding a setting AddToPluginsMenu

https://nopcommerce.codeplex.com/SourceControl/network/forks/hezyz/ExtendIAdminMenuPlugin

hope it will be merged
10 code lines

thanks