1. Purée papaya in a blender with frozen yogurt, 1 tablespoon agave nectar, and lime juice. Pour into a chilled serving glass.
2. Rinse blender, and purée kiwifruit, reserving 1 slice, with remaining 1/2 tablespoon agave until smooth. Spoon on top of papaya mixture, and garnish with kiwifruit slice; serve.