I got this recipe from the guy who owns the preserving food group on Yahoo. He actually makes it in the crockpot.

He uses in corn chowders, potato soup, etc.
I haven't made it yet but am going to ASAP.

Corn Stock

1 tb Canola oil
1 Spanish onion; chopped
2 Carrots; coarsely chopped
2 Stalks celery; coarsely
-chopped
1 ts Salt; or to taste
4 lg Ears fresh corn; kernels
-removed and reserved for
-chowder
2 qt Cold water

In a soup pot, heat the oil. When it is hot, add the onion, carrots,
celery, and salt. Cook over medium heat, stirring often, for 10
minutes.

Turn the heat to medium low, cover the pot, and continue to cook the
vegetables for 10 more minutes.

Snap the cobs in half. Add them to the pot and pour in the water.
Bring the mixture to a boil. Turn the heat to medium low and simmer
the stock for 30 minutes.

Set a colander over a bowl. Strain the stock into the bowl and set
aside. Discard the vegetables.

MAKES 2 QUARTS

Dede's note: can be canned as for veggie stock.
Pints 30 minutes/quarts 35 at 10 lbs. pressure (adjust for your altitude)