This year at Alta View, we decided on a book return contest for the classes. We made a chart with butcher paper and teacher's names. By each name, we measured a large rectangle according to the number of kids in each class. The squares were from a dye cut, and when a student returned all of their books they got a square and glued it to the poster. This gave the kids a visual reminder of their class progress towards getting all books in and fines paid. The first classes to have all books and fines in were given a treat.
The kids LOVED it, and they encouraged their classmates to get their books in.