Help site visitors connect. Seen any tools like this?

Here is a fairly vague question for a SitePoint forum; but, I see no way around it.

I am wondering if a certain type of application already exists…if there is already something similar to what I am about to describe that I have just not seen before (not being familiar with social apps). My new site will be promoting a type of pledge, or “challenge”, and it might help if users saw that their friends had “signed on” to the pledge. I would like to provide a simple way for site visitors to connect with one another.

Scenario: You have visited the site and have “signed on” to the challenge. Then, you send you pass an invitation to a friend…to check out the site (email, Facebook comment, etc.). If they decide to accept “The Challenge”, they should be able to find your name…to be able to designate that affiliation or association when they “sign on”.

If possible, I would rather that users not be required to have “accounts”, to avoid requiring formal “registration”. Yet, I want Sally to be able to see that her friend Joe has signed on, and let Sally look to see all of her “pledges”.

I would look for examples or tutorials if I knew what to look for. Does this remind you of any sort of PHP application or social networking tool?

What website/CMS platform are you currently using?

Most of the site will ride on WordPress, and I do have some experience with that; however, I could also work with a modest PHP<=>MySQL application, given enough of a start.

Just curious…three times I have received notice of a reply to this thread (see screenshot, below)…

…only to open the link and find no such reply.

Is it common for SitePoint users to post a reply and soon delete their own remarks?
Do forum gnomes scour the posts for short or otherwise-lacking posts for deletion?
Are you reading this, now…or am I just dreaming?

Ok, that seems a little odd but I am surmising that the person replied just to get a back link. Forums do attract a lot of spammers these days and they always post something off topic

Yes, indeed. If you look at the e-mail in your screenshot, you’ll see:

Here is the message that has just been posted:

This information is interesting

Comments like that add no value to a thread, and are deleted as fluff.

Thank you for your feedback, Kiwiheretic and TechnoBear. And, to add an update to this topic…
A thoughtful SitePoint user suggested (in IM) that a “petition” might be what I was looking for; so, I have been looking at several petition tools, several that are hosted and some openly available (like PHP Petition).
Will post again if I find solution worth mention…

Thanks for the update azwaldo - no idea why the person answered the thread via a message as it is not that helpful to others reading the thread.

Wouldn’t that require formal registration? I am afraid I’m having trouble getting my head around this one. I thought you were looking for some kind of “affiliation” plugin