I just want to pipe in that, in place of boullion cubes, you can just use fresh herbs and/or veggies in with the chicken before you start cooking it. I like mine with onions (sliced or cubed) and either garlic or ginger, carrots, and sometimes celery and a bay leaf.
I generally bake the chicken with onions and garlic and/or ginger, serve that with one meal, then take what's left of the bones and drippings, put in a big pot, add water and some more veggies and let it simmer for several hours (or overnight) for a delicious broth. Then I remove the bones before serving.
Another trick for quick tasty broths without using boullion cubes is to use vegetable juice. I use whatever veggies I have on hand (broccoli stems, carrots, celery, etc) and put them through the juicer and add the juice to the cooking water. Using enough good, natural salt (but not too much!) also increases flavor without resorting to "chemicals" that are often found in commercial boullion cubes. I usually use vegetable juice in vegetarian broths, since they don't have the bones for extra flavor.