The co-op has business meetings and a seminar one night a month. I missed the one last month due to a vacation, so Gail gave me a little homework to make up for it: cleaning all of the play food and dishes. My son was delighted to have three bags of toys arrive at our house!
Also on the topic of cleaning, one of the duties that someone does each day is straightening up after our session, taking out the garbage if necessary, running the vacuum over the carpet, etc. It seems like things get cleaned up pretty well after the snack, and the older kids know how to put things away, so it does not take more than ten minutes. This way, the class that follows starts in a tidy place.