I found your description of the Facebook invite contacts function and I wonder if there is, or will be, similar functionality for contacts of a user on LinkedIn, Twitter, Google, or just an addressbook.
I also saw comments about your module overriding the Joomla login module, but I use CB Login.
We want our site to be invite only. I don't see how a mass invite of Facebook contacts can generate the required unique invitation codes. The user needs to go to a registration page with some fields hopefully pre-filled from LinkedIn or Facebook, but additional fields required...
I don't think JFBConnect will do what you're looking for. Our Facebook invitations feature is limited due to limitations in what Facebook allows. We also are expecting each social network to further limit notifications, invitations or solicitations even further after the privacy intrusions that have been exposed lately. Facebook (and just about any other social network) is severly limiting how a website can communicate with it's own users and nearly (or completely) eliminating all methods to reach out to users that haven't already approved your site to reach out to. So, unless a user has already granted your site or your users permissions to contact them, you wouldn't be able to send them an invitation or other communication. It's somewhat a catch-22, although there are still some cases where invitations make sense (like a game 'inviting' the user to come back for a reward, etc).
We don't plan to extend our invitation functionality feature much further right now and never plan to extend it to a general address book. There are other extensions meant for mass mailing.
Finally, as for letting users register with a social network, JFBConnect can definitely help with that. We also can respect the admin activation settings on your site, which would allow a user to register, but not use your site until they've been approved by you. We have methods that allow users from a specific domain register on your site as well without activation, but it sounds like you're looking for a more generic audience than that, so the admin activation is the only way I could recommend from what I understand.
I hope that helps explain, but if you have any other questions, just let us know.
JFBConnect let's you setup profile import for any of the social networks we support. For LinkedIn, we support most of the fields they allow for importing, and are always working to update as they make changes. The current documentation shows the following fields available to import: developer.linkedin.com/docs/guide/v2/people/profile-api#me
How you invite users or get them to your site is up to you. You can easily present them with social login buttons to allow them to authenticate and have their profile imported