In a large bowl, dissolve lime gelatin in 2 cups boiling water. Add 2 cups cold water; stir. Pour into a 13-in. x 9-in. dish; refrigerate until firm but not set, about 1 hour.
In a large bowl, dissolve lemon gelatin in 1 cup boiling water. Stir in marshmallows until melted. Cool for 20 minutes. In a small bowl, beat cream cheese and mayonnaise until smooth. Gradually beat in lemon gelatin. Stir in pineapple. Carefully spoon over the lime layer. Chill until firm but not set.
Dissolve cherry gelatin in 2 cups boiling water. Add remaining cold water; stir. Spoon over the lemon layer. Refrigerate entire gelatin salad overnight. Cut into squares to serve. Yield: 12-15 servings.