Combine the sugar and water in a 1 quart saucepan over medium heat and bring to a boil.
Boil gently for 5 minutes.
Chill, covered, until cool.
Combine the sugar syrup, orange juice, grapefruit juice, lime juice and lemon juice in a 6 quart container.
Stir in the ginger ale just before serving.
Serve over ice.