Can be used in a variety of ways:
(and tons more!)
I currently use these as an incentive for students to put forth all effort on any given assignment. Any time a student receives an "A" on an assignment, they bring the card and their paper. I hole punch both, the paper and the card. When students complete the card, they get they reward we agreed upon as a class (right now, our class incentive is a free homework pass).
I'd love to hear how you plan to use yours!