I live off of these to fill me up and keep me going with very little calories. It's mostly water with a little yogurt and milk for flavor. The water and the foam created from the blender is what fills you up.
1 tablespoon of FF yogurt, like Dannon Light 'N Fit
1 tablespoon FF dry milk (dry milk foams; other milk doesn't. I prefer the foam because I "eat" it off the top with a spoon and it's filling)
dash of salt (brings out the sweetness)
sweetner to taste (Equal, Splenda, Sweet'n Low or a mix of all three)
few bits of fruit if you want (very tiny bits of banana or strawberries can be quite flavorful, but not necessary)
Toss that into a full blender of water, like 1 liter. Blend fast for 5-10 seconds, making it foam up at the top (it's very weak, so it's mostly clear...but has flavor if you add enough sweetner and mix the right amount of salt to bring out that flavor). Use a large spoon to "eat" off the little layer of foam on top. Blend again, creating more foam. I "eat" the foam off the top all the way down to where there's hardly any left. Then I'm full with the bubbles and the water and it's actually pretty tasty.
I'm just weird, but aren't we all? Never hurts to share ideas.