This extension will allow your customers to refer their friends via email or Facebook.

The customer frontend has a nice interface where they can go to refer their friends and it shows them if the status of their referral links that have been sent out. If a customer applies a coupon to the order, it will remove the affiliate discount.

The admin backend is configurable to allow for giving the referred customer a discount when they checkout and also to give the referral customer store credit or rewards points. You can even make it so the referral customer will get rewarded anytime their referred customers make an order.

Orders in the admin backend have also been upgraded to show who received a customer referral credit for an order and allow you to add/remove the credit from an order.

Demo available @
http://opencart.bigpayout.com/index.php?route=account/referral
Email: test@bigpayout.com
Password: test

http://opencart.bigpayout.com/admin/
User: demo
Pass: demo