We keep a crockpot going just for this. It gets heated up about two-three times per day and new "stuff" gets dumped in whenever the level get too low, or the soup gets too 'watery"...
Keep your bones, either into the pot or freeze until you have enough to be worth cooking.
Reading my original post, they mention using the "brown" part from the top of onions... I'm not sure which part that actually is... I use onion skins for compost in the window garden. I don't think I would like to eat the dry skins, even cooked, but then I'm not really hungry right now...