1. In a 1- to 1 1/2-quart pan, mix 6 tablespoons sugar and 1 teaspoon gelatin. Stir in whipping cream; let stand to soften gelatin, 1 to 2 minutes.
2. Stir cream mixture over medium heat until sugar and gelatin are completely dissolved and mixture feels smooth, 3 to 4 minutes. Pour into a 2- to 4-cup glass measure and stir in vanilla. Let mixture stand until just warm, stirring occasionally, 10 to 15 minutes. Pour into 12 shot glasses (3- to 4-tablespoon size). Chill until firm, 1 1/2 to 2 hours.
3. When panna cotta is firm, make toppings: In a 1- to 2-quart pan, mix remaining 1 teaspoon sugar and 1/2 teaspoon gelatin. Add 1/4 cup water; let stand 1 minute. Stir over high heat until mixture is simmering, 1 to 2 minutes. If making only one flavor, stir flavored syrup or liqueur into mixture; if making four, pour gelatin mixture equally into four small bowls and stir 2 tablespoons syrup or liqueur into mixture in each bowl. Let cool to room temperature, 2 to 5 minutes.
4. Spoon about 1/4 inch of the cool topping over each firm panna cotta shot. Chill until firm, at least 1 1/2 hours.
Note: Nutritional analysis is per shot.