Perfect for storing small portions, I use these to hold leftover oatmeal. Just don't microwave the lids, as they shrivel and get wrecked.
These heat resistant glass bowls have airtight plastic lids and are perfect for storing up to 16 oz. of leftovers or whatever you need them for. Each set is dishwasher and microwave safe and can be purchased at Crate&Barrel for $1.75 each.