Make the celery ice: Pass celery and fennel through an electric juicer (you should have about 3 cups). Stir in lemon juice; season with salt. Pour into ice-cube trays, and freeze (up to 2 weeks).
Pass tomatoes and juice through the medium disk of a food mill or coarse sieve into a large bowl; discard solids. Stir in the Worcestershire sauce. Transfer to a pitcher, and refrigerate at least 1 hour (up to overnight).
For each drink, combine 3 celery ice cubes, 6 ounces tomato mixture, 1 ounce aquavit or vodka, 3 dashes hot sauce, 1/4 to 1/2 teaspoon horseradish, 1/4 teaspoon salt, and a pinch of pepper in a 12-ounce glass. Serve each drink with a lime wedge and celery or fennel leaves and stalks.