Members Only is a Joomla plug-in that hides part or your full-website's content from anonymous visitors. You are in TOTAL CONTROL of the kind of community you are building.
* Single use invitations. Option to delete invitation codes once they are used
* IP Address Filter. You can set a whitelist of one or more IP Address/IP Range to allow access. In addition you can set a bypass for users with certain access level
* Allow search engines to access the website.
* Advanced search engine identifier using Http:BL from the ProjectHoneyPot
* Registration NOT allowed. Only you control the user's list of your website. Every visitor must have a pre-existent username.
* Registration allowed without invitation. This is similar to usual registration process but the visitors can't see your site's content unless they register and log in.
* Registration allowed by invitation. Any visitor that have the right Invitation code may register.
* Invitation control. You control too if the visitor can apply for the invitation, if the invitations are automatically sent or you must send them manually.
It installs pretty easy, no uncompatibility with my site detected.
Members Only is a Great Extension!!