Don't ever throw away the green tops of leeks! After using the white bottom part in whatever delicious thing you are making, throw the tops in a bag in the freezer. When you have a few minutes, put them in a stock pot with garlic, herbs of various sorts and any other veggies you have lying around. Boil them for about an hour or so, strain out the veggies, and you've got really good vegetable stock. Put it in mason jars and freeze 'em. Good veggie stock is a valuable, valuable commodity in the kitchen- and it costs about four bucks a quart at the supermarket.
Tonight I used this stock to make a tomato paella that was ridiculously good. With a salad and a loaf of Em's fresh baked bread, we were eatin' good. And I have four quarts of leek stock in the freezer.