My mom recently found these bowls at a local store and of course bought some for her dietitian daughter. While they may not work well for cereal, I have found the 1/4 cup to be perfect for ice cream! They also the perfect size for yogurt, fruit, and cucumber salad. (Not all at the same time...) To save space they stack/nest inside each other. These bowls would work well for people trying to focus on portion control or carbohydrate counting. There are several different companies that make portion bowls and plates; to purchase your own check out these sites to see which you like the best.
tag2u.com
shopmeasureupbowl.com
preciseportions.com
portionware.net
yumyumdish.com