Magento Refer a Friend Extension

Magento refer a friend extension allows you to invite your customers to market your products and offer them discounts and bonuses. You can attract your customers to become your affiliates and invite more customers to buy products from you. In return, you can offer them discounts and bonuses according to referrals. You can create different rules to reward your customers.

Magento refer a friend lets you create a unique broadcast link which customers can use to invite friends to your store. You can reward the customers when its referral signs up. Also configure the type and amount of discount offered. Customers can see all their referrals in ‘Customer Account’. You can view all your affiliates with their discount amount in ‘Manage Discounts’ section. Edit the discount amount in percentage and write comment for the customer. 

See full features: https://marketplace.magento.com/fme-referafriend.html