Most things can be added to a soup or a stew, except the heavily tomato leftovers. Thos though can be mixed either into a new marinara sauce or a chili. They can also be put on garlic bread with some mozz and baked in either a toaster oven or conventional oven. Oriental foods can be remixed as well, or added to ramen for a decent oriental soup. Leftover chicken can be chopped up into either a chicken salad, soups or cut larger and put into an alfredo. These are just a few ideas. Omlettes are a good use for many leftovers too.