Lately i have been experimenting with a recommendation component, i have cleaned out the component as it was a mess and now it loads up with your own name and email address, to make it better and it would add this invitation to the database.
It would be very easy for me to integrate this so when the user went on the homepage it would add a point, just like a referral module been done.
It is very complicated to add points when a user is registered - where for example the cb api doesn't permit be to enter a form value in already. Also it isn't straight forward at all and especially on some sites, it could lead to spam mailing.
as going on a page is okay - yet sending out emails to signup isn't and for some reason including me wouldn't like it.
Anyway i will finish off the basic thing - and then i'll let someone mess around with it - as i want to concentrate on something straight forward but still very useful.