In a large bowl, whisk together the lemon juice, vinegar and salt. Add the oil in a slow stream, whisking until emulsified. Add the watermelon, arugula and pine nuts. Toss to coat. Taste and adjust seasonings.
Per Serving: 102 Calories (64.5% from fat); 8g Fat (1g Sat, 4g Mono, 2g Poly); 2g Protein, 7g Carbohydrate; 1g Dietary Fiber; 0mg Cholesterol; 164mg Sodium. Food Exchanges: 1/2 Fruit; 1 1/2 Fat.