Close! Though we do LOVE It when people use the tellafriend!
The forum referrals are something we only really used once for a purpose. In the FAQ, it will show you a url you can give someone that might be interested in joining the forum.
Mine is
http://www.3fatchicks.com/forum/index.php?referrerid=3
Every account here has it's own user ID number (you can change your username, so the script tracks you by a user ID), and the referral link includes your account number on the end. If someone joins and uses your link (or referral ID number) then it shows on your forum account as a referral.
We once had a contest to promote the forum, and the person that had the most referrals after a month won an Amazon gift certificate.