If you're a health nut, add 1 tbsp wheat germ.
Or if you have issues with digestion, add 1 tbsp flax seed.
You could also substitute frozen yogurt for the ice cream, or active culture regular yogurt-just add more ice to make the consistency nice and "shake-style".
Give this a go today. It's supposed to be warm in England this weekend-whoop whoop!
Life is too short to miss out on milkshakes! :)