A few great ideas from Professional Organizer Maria Gracia:

In the kitchen:

Binder clips or clothes pins can be used to close bags of chips or other foods

Plastic jar lids are useful under bottles of honey, cooking oil and other kitchen foods that often drip down the side

Do you have extra measuring spoons cluttering a drawer?  Drop one into a canister of baking soda, sugar, oatmeal etc. for when you need a quick measure.

In the storage room:

If you buy large plastic containers of salad greens, the empties are great to store various craft supplies

Fold extension cords and place inside empty toilet paper or paper towel rolls to keep them from tangling

Old suitcases are great for holding outgrown kids' clothes that are being save, seldom used clothing (ski clothes, bathing suits) or old papers that you want or need to keep but are not likely to be needed soon.  Make a note of where you stored them!