When we have a popular activity, we use a waiting list. Our waiting list is usually a simple scrap of paper taped or posted near the activity.
We add names to the list or kids print their own names. Then they can go do other things. When a child's name is next on the list, I go to him and tell him it's his turn. He has the option to take his turn or continue whatever else he is doing.
We line through names as kids take their turns. A child who doesn't want to take his turn is move to the end of the list for a later turn.
If an activity is really popular, we will continue the activity for the next week, and keep the waiting list, too. Kids at the top of the list are first the next time.
In addition to keeping things orderly, waiting lists help build literacy. Kids begin to recognize their names and the names of their friends. They also see writing used in a practical way, part of understanding how reading and writing work in the world.