Place the gelatin powder in a small mixing bowl. Pour 1/4 cup of cold ginger beer over the gelatin and whisk to combine. Let the gelatin soak into the beer while you prep the other ingredients.
Pour the rest of the beer into a small saucepan and bring to a simmer over medium heat.
Pour the warm beer over the gelatin and whisk to combine. Be sure the gelatin is completely dissolved.
Add the vodka and lime juice to the beer mixture and stir to combine.
Place the plastic ramekins (lids off) on a small baking sheet. Fill each ramekin almost full with the jello mixture.
Place the baking sheet holding the ramekins into the refrigerator and chill for 2-3 hours or until the jello has set up.
When ready to serve, remove the shots from the fridge. Place a quarter lime wheel on top of each shot for garnish, if desired. Serve immediately.