Did you know: you can buy cheap, vile soup, and turn it into cheap, tasty soup? It's true!
The nice thing about this technique is you don't get stuck with a large amount of leftover soup, as you tend to when making it from scratch. Some folks advise us single cooks, "Oh, just buy in bulk and store it in the freezer!" Nice try, but I have to share a fridge with flatmates (and it's one of those icky miniature European refrigerators, too. Just try stashing a gallon of soup in one of those things even on the best of days.)
I have one friend who lives alone and pretty much lives off of soups. I think he said he usually spends $1 a day on eating -- that's the magic of soup.
You can add spices, cooked meats, cooked vegetables (don't use raw unless you either want them to stay crunchy or you mean to cook the soup a looong time) or sauces to the soup as it's cooking.
You can add to finished soup any suitable fresh herbs, crackers or croutons, bread slices, nuts, or top them with favorite condiments and sauces.
For some ideas, "Mexican Style" Cream of Tomato soup is made with added onion, garlic and cooked chicken to the pot, with sour cream and cilantro for garnish. The famous French Onion Soup is generally dished out with a chunk of toast or crouton inside and topped with a thick layer of white cheese (mozzarella, gruyere, swiss, etc) which is put under the broiler before serving. I've actually bought Broccoli-Cheese Soup mixes that told me to add my own broccoli and cheese (probably it just starts as any type of cream soup...). And Scotch Broth simply tastes better, I think, if you douse it in Tabasco sauce first.
What kind of soup alterations do you fellows make? Leave a comment -- describe your favorite creations!