Sevens
I learned this game at the 2005 OCA Conference, at the "No Equipment, No Planning Time, No Problem" session facilitated by Matt Barr.
Girls playing this game must understand the concept of multiples of 7, e.g., 7, 14, 21, etc. Place everyone seated in a large circle, facing inward. Choose one person to start the game by saying "1". The next person continues by calling the next number in sequence (e.g., "2"), and so on, until the group reaches "7". The person who would ordinarily call "7" claps once instead, to represent the first multiple of 7. Continue counting around the circle, substituting the appropriate number of claps for each multiple of 7 (e.g., 14 would get two claps, 21 would get three claps, etc.). You can either do this as an elimination game or as a cooperative game, with the objective of reaching 100 with no mistakes.