Pressure cooking greatly reduces the time and effort necessary to make great stock.

Step 1: Brown Soup Bones

canola oil
1-2 lbs soup bones
7qt pressure cooker

Add a dollop of canola oil and the soup bones to your pressure cooker over medium heat. Stir occasionally so the meat/bones brown.

Notes:
Soup bones are usually sold as cheap extras, though you may need to specifically ask your butcher if they're not already set out. I prefer to use soup bones from grass-fed pastured cattle or bison due to their lower fat content and better lipid profile.

Pressure cookers vary greatly. I've got a 7qt Kuhn Rikon, which I love dearly. The new pressure cookers are much safer than the old ones that just had a weight set atop the lid, so get one of the newer style if you can. The Kuhn Rikon pressure cookers have multiple safety interlocks and emergency bleed valves. They can be a bit pricy, so I highly recommend checking eBay for a better deal, new or used. Replacing the gasket on a used pressure cooker makes it as good as new.

Step 2: Add Vegetables

2 onions
4 stalks celery
4 carrots
1/2 bunch parsley

Coarsely chop all of the vegetables, add to the pot, and stir.

You may use other root vegetables such as turnips and parsnips, but steer clear of any members of the cabbage family. Cabbage, cauliflower, broccoli, and the like can impart a strong bitter flavor to the stock. Beets will turn the stock a bright red/purple, so use with caution.

Step 3: Add Spices

Spices:
2 bay leaves
5 cloves garlic, halved
pepper corns
mustard seeds
coriander seeds

Optional::
cloves (not too many; they're strong)
dried chipoltle pepper (surprisingly subtle and tasty)
allspice berries (one of my favorites)
lemongrass (the resulting stock is quite fragrant)

Add the spices of your choice and stir.

Step 4: Add Water

Add 10 cups of water and stir.

Step 5: Cover and Cook

Wipe the sealing surface of the pot, then close and lock the lid.

Turn the heat up to high, and cook until the pressure indicator reaches the 2nd red ring (15psi). Turn the heat down to low and cook for 1 hour, maintaining the pressure at the 2nd red ring.

Move the pot off the heat and allow it to cool. This may take about 30 minutes or so, depending on the ambient temperature.

Step 6: Open and Drain

Set a large bowl (capable of holding >12cups; the veggies drop water too) in the sink, and place a strainer or sieve above.

Open the depressurized pot and wait for the steam to subside. Carefully pour stock through the sieve, taking care not to let too many chunks fall into the strainer. When you get near the end of the pot turn it upright, give the contents a good shake, and pour out the other side. Repeat as needed, using a spoon to hold back the chunks if necessary.

Dispose of the solid bits: the meat and veggies will have imparted all of their flavor to the broth, leaving a tasteless mush you probably don't want to eat unless you're a starving student.

Step 7: Use or Store

You've now got a steaming-hot bowl of brothy goodness. What to do with it? There are a couple of options.

1) Use immediately in a tasty soup. This would require proper planning, something I'm not terribly good at.

2) Refrigerate for use in the next few days. This enables you to skim any congealed fat off the surface before use. I used this batch of stock for onion soup.

3) Aliquot* and freeze. I use those cheap reusable plastic containers they sell by the sandwich baggies. Make sure to label the lids BEFORE you cover the containers, and leave enough space for the broth to expand upon freezing. Again the fat will congeal at the surface, so you can scrape it off before thawing and using your stock.

*aliquot = a biochem term meaning to divide (as a solution) into equal parts