One of the cabinets under my kitchen sink is stuffed full of these wimpy, plastic grocery bags. There must be around a hundred of them in there at this point. The only reuse I get out of them is to take lunch into work. I decided I should start bringing my own bag, so I bought these reusable bags from Schnucks at five for $4.
They're great! It turns out I can stuff over 20 lbs of groceries into just one bag: all that stuff pictured above except the gallon of milk, which provides a good size reference. As a revealing comparison, I've lost about one and a half reusable bags worth of weight since I started working out regularly in January.
Head to Cockeyed.com to find out how much is inside other stuff.