Drip some water (maybe a 1-2 teaspoons) on the slices, then put them in the oven for a few minutes. If you take it out in time, you'll have nearly fresh tasting bread. If you take it out a few minutes late, you have toast.
My mum used to make mini pizza's from stale French bread. You slice it in half, spread some tomato puree on the bread, your favourite pizza toppings and a bit of cheese, then put it in the oven until the cheese melts.