Planned-overs is what I call it when I make too much food one night, so that I can turn it into something else for another night's dinner. Right now, I have chicken broth, salsa, leftover soups, summer-fresh diced tomatoes, and cooked beans in the freezer waiting for us. If I take them out tonight they'll be ready for tomorrow.
Roast chicken is a good illustration of this: I cook the chicken in my oval slow-cooker. That night, I remove all the meat, then add more water to the crock and make sure all the bones are covered. I set it to cook on low for 10 hours and leave it until I get home from work the next day - it will automatically go on the warm setting until I turn it off, so it will still be warm. I pour the broth through a strainer and into a large container and discard what gets caught by the strainer. The broth is put in the fridge for 24 hours to chill. I skim the fat from the top, and freeze the broth. Often I'll freeze a quart canning jar with 2 cups meat and 2 cups broth, label it, and it will be the base for chicken soup or pot pie later on. My "leftovers" become, quite frequently, two to three other meals which may generate their own leftovers (potpie lasts two nights, here; it's very filling).
Roast beef is much the same way. Cook a roast in the slowcooker, with enough water to cover, and it will make dinner with a delicious, meaty broth that can serve as the base for wonderful stews and potpies. Cook the broth with lentils, barley, carrots, and sauteed onions and it's a wonderful, easy meal. Don't leave out the spices when you cook the meats; just keep them in mind when you decide what to use the broth for so that the flavors will complement each other, or blend - not fight.
Dry beans can be made ahead - soak, cook, and then freeze in 2 cup amounts (the same as a store-bought can) and you get better quality food that's nearly as easy for half the price.
Spaghetti sauce or chili can be made in large batches and frozen in 3-cup portions - dinner for two, or serve over rice or pasta for three. Add a fresh salad and you'll enjoy the compliments without the work.