Back in elementary school, my math teacher gave out virtual money (in the form of xeroxed monopoly money stamped with a special seal) to students who completed homework assignments and those that did well on tests. One day out of every week, he would bring a bunch of goodies (e.g. mechanical pencils) to class and auction them off to the highest bidders with these monopoly money. The auctions were very enjoyable since it was interesting to see people outbidding each others in the process. Being much of a saver myself, I accumulated a huge sum of these monopoly money and kept all of them in one of my 3-ring binders. One day, I discovered someone stole all of them while I left my backpack unattended. After telling my teacher about it, he told everyone to open their backpacks and inspected them. However, we never found out who stole them and it sucked because after that incident, I started to distrust some of my friends. I think this system could be improved if the rewards were non-tranferrable. Perhaps someone can build a web application that lets teachers employ such technique and allows students to accumulate money in the digital form?