Oh my. I just made the best soup from the rib roast bone (see previous Horseradish and garlic crusted prime rib post).
After we ate the rib roast, I kept the trim and the bone. Rather than let it rot in the fridge, I cut some mirepoix (roughly chopped onion, celery and carrots) cut the bone apart, and covered the mess with water. I used a tall, narrow stock pot to minimize evaporation, and cooked the mess for a couple of hours. I strained it, picked the meat off the bone, and chilled the broth and meat. I defatted it, added more mirepoix, and cooked some inexpensive mini ravioli's.
The resulting soup is marvelous. The meat is still beefy and the broth hearty. I like the mini raviolis in soup and I do so love making the most of everything I make.