SuperPoints has really gained popularity and the easiest way to join is with a SuperPoints invite. As of 2/9, they moved to a static referral link, which eliminates the timed token invites that used to be sent out. I think this is a wise move that will help grow their base.
SuperPoints works somewhat like Swagbucks in that you earn points for doing offers, tasks, the Super Lucky button, inviting friends, and more. These points convert to gift cards and the more friends you have, the faster you earn rewards. So once you join, ask your friends to join too. SuperPoints would be a great rewards program for college students to help them earn money away from home.
Superpoints referral link