ACME Bags - EarthTote Reusable Shopping Bag
Made from recycled PET and tough enough to hold an angry weasel. Lots of room for larger items like 1/2 gallon cartons of juice or boxes of cereal, although you may need two or more if you're really stocking up. I also like that the inside resists moisture and spills, so it's easy to keep clean. I'm sure this heavy duty bag can be used for various other purposes as well.