We bought a juicer off craigslist today. $180 brand new, and we got it for $40. Erinne had carrot and apple. I had carrot, apple, beet, celery, and whatever else I could find. It's a centrifugal juicer, which isn't as efficient as the other kinds, so we had a lot of pulp leftover. I decided to learn how to make vegetable stock, and here's what I learned...
When you cut up a vegetable, there are always inedible parts that you throw away. Don't. Save them in the freezer to use for vegetable stock later. Celery leaves, the ends of carrots, onion peels, basically everything is useful (don't use potato peels, they make it starchy)! The ratios are not important. Cook everything for, I don't know, about an hour, then strain. I might not ever throw away vegetable scraps again!
EDIT: Ok, technically I will still be throwing away the scraps, but only after I've used them.