Click on Manage Referrals. It is in your home portion of DB, just to the right of where a profile picture would go or is in the bottom of the box labeled Refer a Friend.
This page will show you how many referrals you have sent that remain unfilled as well as a list of those who have joined through you below that. Those who join by referral will have the date they joined (newest has the lowest number designation), their first name, and their user name. Hope that helps!
BTW Greg, this is supposed to be an anonymous forum. Where`s the forum police (aka moderators) when we need them!