There should be like a trivia, or a quiz on rulings, where you PM the answer to a certain admin (whoever wants the task) and depending on the grade you get, you get a certain OD reward.
Or maybe a challenge, like put you in a certain situation in a duel, with certain cards in the hands, fields, graveyards, decks, extra decks, and banished piles of both players, and give the person three tries to win in one turn, and they get a certain amount of OD depending on how many tries it takes.