In a heavy saucepan combine gelatin, cinnamon, ginger, nutmeg, and salt. Stir in condensed milk and beaten eggs, mixing well. Let stand one minute, then place on burner over low heat, stirring constantly for about 10 minutes, or until gelatin dissolves and mixture thickens. Remove from heat.
Stir in pumpkin and vanilla, mixing thoroughly, and pour mixture into graham cracker crusts. Chill for at least 3 hours before serving.