Put the giblets, the celery, and the onion in a 3.5 qt. saucepan with a pinch of salt, bring to a boil, and keep at a low simmer for 2-3 hours, or until the giblets are tender. A few notes: turkey giblets often include the liver - this will overpower the gravy, so discard it (or cook it separately and feed it to the dog). You want to keep the giblets at such a low simmer that not much water evaporates - you could also try the crockpot for several hours. The endgame is that you want the giblets to be tender when pierced with a fork. Pull out the giblets, chop them finely, (removing the bones of the neck) and set aside. Discard the celery and onion, but keep the stock you've just made, which can be refrigerated until you're ready to use, but should be reheated to a simmer before making gravy.
When your turkey is done roasting, combine ½ cup turkey drippings with ½ cup flour in a saucepan, mix until there are no lumps, and cook for about 5 minutes, to lose the raw flour taste. Add warmed stock, beginning with 4 cups, add more until the gravy is the consistency you like. Just before serving, add the chopped giblets.
Recipe by The Domestic Front at http://www.thedomesticfront.com/things-that-are-important/