Grenadine is used to flavor sodas (Shirley temple comes to mind) and cocktails. You may also see grenadine used as a layering agent in many cocktail shooters or cocktails like the tequila sunrise.
Fee Brothers American Beauty Grenadine
12.8 fluid oz. (375ml), syrup for mixed drinks, great for dessert toppings and coffee flavoring, glass bottle design
Stirrings Authentic Grenadine
12 oz bottle (355ml), grenadine made with cane sugar, no high fructose corn syrup, refridgerate after opening