Quart sized freezer bags. You probably throw them away every week if you buy frozen vegetables. Those bags are freezer bags. They wouldn't sell them in those bags if they weren't capable of keeping the vegetables fresh and frost free. Cut them carefully across the top when you open them and use a twist'em tie or rubber band to close them securely when you fill them.
Refrigerator containers. Cottage cheese, sour cream, yogurt and more come in resealable plastic containers that can be used over and over again. Get some cheap masking tape to label the contents. A bonus is that they're ultimately stackable and hold more than they look.
Canisters. Storage jars are free. Really. Check your local restaurants to see if they will save you a few gallon jars. They buy them with everthing from pickles to boiled eggs in them. Most come with sealing lids so your flour and sugar will be safe. You can also use them for beans, pasta and other food products.
Compost. Make your own, of course. That's a no-brainer, but sometimes it's hard to accomplish, especially if you have limited space or it isn't conveniently located. Invest in a bowl with a lid to hold your compostable kitchen scraps and simply dig a hole in an out of the way place in your yard and dump the goods in there. Cover them with dirt and that's it. It will take longer to make if you don't turn it now and then and if it's dry, but it will eventually make good compost. Hurry it by turning and keeping it moist.
House slippers. If you have a warm sweater or one that is felted accidentally or otherwise, simply make a pattern by standing on a newspaper and drawing around your foot. Cut two pieces to match this pattern, then measure along the side from toe all the way around and back to the toe and cut a strip about two to three inches wide this long. Sew the strip. starting at the toe, to the sole so it's the side, then gather the edges of this strip with a piece of sturdy yarn in a needle, weaving back and forth. Draw the yarn up so that the shoe fits your foot and tie a knot, then a bow. Done.