I read about kale smoothies in that font of epicurean knowledge, 
Parade Magazine.  The recipes sounded really weird, but since leafy greens are not a strong point in my kitchen, I gave it a try.  Wow!  So good!
Here's a basic recipe, but you can use whatever you have on hand.  The banana gives the smoothies the underlying sweetness, so I always include banana.  I've used a peach, a large handful of strawberries, etc.
Banana-Kale Smoothie
Serves 2
1  banana
1/2 cup of blueberries (if frozen, nuke for 20 seconds)
1 large kale leaf, tough central stem removed
     (Can also use 3/4 - 1 cup of spinach leaves or chard)
1/2 to 3/4 cup of water, milk, yogurt or soy milk
Blend in a blender or food processor.  Kale requires a 30-45 seconds of blending, less for chard or spinach.