Getting Friends Via Invite

Seem that this method by far is one of the best way to add new friends. But i'm facing in getting new email who will probably have facebook account.

By far i've tried:
Add me groups on FB who have e-mail lists
Twitter email collecting script
Fast Email Extractor

Non of this methods gave me enough emails to supply big number of account. Any other more effective way to get big numbers of emails per day.

Thanks