My latest attempt in this regard is this delicious watermelon drink. The ingredients couldn't be simpler: watermelon and coconut water (I used about 3 cups of watermelon and 250 mls of coconut water, but you can vary this according to taste). You can use plain coconut water, or a flavoured one. I used mango and it gave the drink an extra dimension. Throw everything in the blender with lots of ice.