I know what you're going to have in your refrigerator and freezer from here until the end of days: homemade chicken stock. "But wait," you're saying. Isn't stock-making really time- and labor-intensive? And why should I make it, when I can buy it at the store? And to that I say: those are stupid questions, and you're a stupid person. Or, to put it another way, good questions. The answers: it does take time, but not too much; if you're going to be at home for the afternoon, it's not a problem—start to finish, it takes about six hours. It's hardly labor intensive. And, while box chicken stock can be okay, this will taste better and it won't be laden with salt—in fact, I don't put any salt in my stock; I wait until I'm cooking with it to add salt, and it turns out just fine. Let's make some!
First, you'll need a chicken carcass. Of course, if you've had brunch recently, that won't be a problem. Take the chicken bones, any meat clinging to the bones (if you have some leftover meat, it's not a terrible idea to throw that in), that gelled chicken juice that you hopefully saved, and throw them in a stock pot. Cover with cold water by an inch or two (less water will give you a thicker stock, more will make it thinner—both are fine) and put over medium, medium-high heat until you get just below a simmer. If you have a thermometer, look for between 180 and 190 degrees. If you don't have a thermometer, look for one or two bubbles coming to the surface very few seconds. When you hit that, lower to heat to low to maintain the temperature.
Then, nothing for five hours. Well, not nothing—you'll want to check the temperature every now and then, and to keep the stock clear, it's a good idea to skim off the...stuff that collects at the top of the pot. From what I gather, it's mostly protein, and it looks like the foam that collects in the ocean on a windy day. The easiest way to do it is to keep a bowl of water and a spoon next to the stove, and every 30-45 minutes, skim the foam off and put it in the bowl.
After about five hours, add your additional flavorings: half a tablespoon or so of peppercorns, a couple of crushed cloves of garlic, a small onion cut into quarters, a stalk of celery, a peeled carrot, some herbs, a few teaspoons of tomato paste, whatever you've got on hand. Let that cook for another hour, then strain—I like to use a piece of cheesecloth or thin kitchen towel inside a strainer. Strain it into a large bowl, and let it sit on the counter for an hour or so to cool it down a bit. Then, pop it in the fridge overnight, pour it into smaller containers (I like those cup, cup-and-a half containers, but anything will do), and either refrigerate for a week or so or freeze.
What's it good for? Well, there's a ton of soup recipes out there, but I'll add a couple of suggestions in the comments.