Don't throw out your Christmas card envelopes and make it your resolution for 2013 not to throw out any other envelope. Open them up and use the backs as scrap paper to write lists on, or for your children to scribble on. You can even trim them up and secure with a mini bulldog clip (find them here on the cheap) to form a little shopping list note pad.
Look at what you're throwing out and find a second use. Help out both the planet and your purse.