This is a recipe developed by dh, wonderful guy that he is. It's not low in calories, but not as bad as it could be - 700 calories using fitday.com (recipe is for at least 2 servings, probably 4 if you're more reasonable).
1 c crushed pineapple (we use canned)
1/2 c frozen pineapple (unsweetened organic if you can find it)
1/4 c cream of coconut
1/4 c coconut milk
1/2 c milk (low fat organic)
Blend all this, add ice to the desired consistency. Add rum if desired.
I call it a smoothie because of the fruit instead of fruit juice. It is really very good!