I've got one of those single serv type of blenders- pefect size for a smoothie.
I'll make one of these for lunch and it will usually keep me full till dinner time-
1/4 cup Frozen Blueberries
3/4 cup Fat Free Vanilla Yogurt
1/2 to 3/4 cup of 1% milk or Soy Milk (Choc or vanilla)
4 ice cubes