NobleCom has a great reward program for their customers referring others to buy phone cards from NobleCom.
If you refer friends and if they sign up then you get $10 in Nobel points for each one of the sign up as a new customer. Also the referred friend earns $5 in Nobel points. There's no limit on the number of friends that you can refer to NobelCom. You'll get more points by referring more. These points can be used to buy more credit or as discounts towards future phone card purchases and recharges.