Facebook now displays detailed invite history to all their users.
1. If you would like to know who all have joined Facebook because of you, go here.
2. If you would like to see a list of all people whom you have invited to join Facebook but they are yet to accept your invitation, go here.
3. If you like to know who in your friends circle has brought the maximum number of people to Facebook so far, go to facebook.com/impact.
The Facebook Invites history page also gives an option to send email reminders to friends who are yet to join the social site incase your previous invites went unnoticed or if they landed in the junk folder.