In fact, we have a hard time getting through a whole loaf of bread so we usually throw half in the freezer and pulverize it into breadcrumbs when we need it. If our bread isn't stale yet, however, we use this process to dry it out and make breadcrumbs.
Remember - if you are purposely letting a loaf of bread go stale, leave it out on the counter uncovered. If it's covered or in a plastic bag it may mold from its own internal moisture. If it's humid, you can also put the bread in the fridge in a plastic bag.
Preheat oven to 250ºF. Slice a loaf of bread into large crouton-sized chunks, or thin slices. Place on a large cookie sheet and bake for about 10 minutes or until the bread is completely dried out. If you are in an especially humid climate or if the bread is fresh and moist, turn off the oven and leave it there all night.
Run the chunks through a food processor until you have fine breadcrumbs - or grate with a box grater.