I forgot to post here my absolute favorite stock recipe:

1 chicken back, raw (or 2-3 cooked chicken backs)
4 carrots (rinsed, but not peeled)
4 stalks celery (")
1 large onion, halved
10 whole peppercorns
2 bay leaves
2 cups parsley (just a big handful, not chopped)
3 quarts cold water (or whatever it takes to cover everything)

Put everything in your slow cooker before you go to bed, set for 10 hours on low, and presto! In the morning, you've got a fantastic stock with almost no effort! Strain the stock through a sieve and then through cheesecloth or coffee filters, if you want (I'd do that if I were using it for a gravy, but for soup, you really don't need to.)

If you want to clarify it, put it in jars and refrigerate for about 3 days. The solids should rise to the top; you can either discard them or use them in soup or for roasting. Any particles will be at the bottom; you can suck them out of the jar with a turkey baster.