Soup Stock

I made chicken stock last night while I was sleeping. Aren't I amazing? Seriously though I learned this trick from Chef Michael Smith while watching one of his Chef at Home episodes.
You take all your ingredients, dump them into a slow cooker, add water, then turn it to "low". Then go to bed! When you get up in the morning you'll have a pot of amazingly flavourful stock *almost* ready for use.

Chicken or Beef Bones for meat stock OR
Vegetables, for vegetable stock

Any or all of the following:
Bay leaf or 2
Whole garlic cloves
Large onion, cut into large chunks
Celery stalk or 2, cut in half
Carrot or 2, cut in half
Any leftover veges you want to get out of your fridge
Splash of vinegar or lemon juice (for meat stock- helps get more calcium into your stock)

Add the bones and cover with water. Add everything else. It's ok if the veges aren't completely covered. Cover your slow cooker with its' lid, turn temperature onto "low" setting, and walk away for at least 8 hrs. I have left mine for up to 24 hours. The longer it cooks, the deeper the flavour.

When you get back to it, strain out the solids, cool the liquid enough to refrigerate, and let it completely cool down in the fridge. If using meat bones you will have a layer of solidified fat to remove before freezing or using your stock. I usually skim off this fat and then use medium freezer bags to store the stock until I need it. Make sure you zip up the bag, removing as much air as possible (to prevent freezer burn), label it with contents and date, then freeze flat- this makes it easier to store frozen stock bags upright so they take up less space.

Some frugal tips:
When cutting up green onions, don't toss out the root and lower portion that you don't use- toss into a freezer bag.
Wash and scrub all your vegetables before peeling them, then instead of throwing out or composting your peelings, toss them into a freezer bag. I have heard cruciferous vegetables aren't as good to freeze- they start to stink like sulfur when they're boiling.
If vegetables are a bit soft- not moldy, just not as crisp as you'd like for a salad or vege tray, put them right into your freezer bag.
NEVER use moldy produce for stock. Those should defintely be discarded in some way.
Remember, remove as much excess air as possible before freezing anything. You will get much less freezer burn.