Here is a great recipe for homemade ginger ale thanks to Whole Foods:
http://www.wholefoodsmarket.com/recipes/recipe.php?recipeId=296

Noah's Ginger Ale
Noah’s Ginger Ale
Make about 2 cups syrup (enough for 32 servings)
Diana from Las Vegas sent us this recipe for a refreshing ginger drink. Her nephew requests it every time he visits. He loves the flavor, while Diana loves that it’s all-natural and helps with digestion. Make a pitcher to add some sparkle to your outdoor parties this summer.
Ingredients
2 tablespoons peeled and diced fresh ginger root
2 cups water
2 cups sugar
Ice
Sparkling water
Cherries
Method
Place ginger, water and sugar in a saucepan. Bring to a boil. Reduce heat to medium and simmer about 10 minutes. Cool and strain. Syrup can be chilled in the refrigerator for a week.
To serve, fill glasses with ice cubes. Add a tablespoon of ginger syrup and top with sparkling water. Stir and top with a cherry. Taste and add more syrup if desired.
Nutrition
Per serving (1 Tbsp syrup with sparkling water and 1 cherry/Volume will vary depending on volume sparkling water used): 45 calories (0 from fat), 0g total fat, 0g saturated fat, 0g protein, 11g total carbohydrate (0g dietary fiber, 11g sugar), 0mg cholesterol, 0mg sodium