When you bake your own bread, you normally have to deal with leftover bread, too. When the bread become stale, I normally place it on top of the kitchen radiator and let them dry out completely. When they are dry, I put them in a food container and keep them for further use, like bribing our guinea pig (not a healthy treat, I know) or crushing them to bread crumbs. The bread crumbs I use regulary for cooking and baking. I like to put them into the filling of sweet pastries. Or I add them into a bread dough, replacing a part of the flour with the bread crumbs.
Lutz like to put old bread into preferments. I like this idea and vary his kind of preferment, so that its made out of bread crumbs completely. Together with some sourdough and a slow and long proof in the fridge, it adds a lot of flavour to the bread. Very delicious!