Some old housemates of mine had a pizza stone and swore by it — and made delicious, delicious pizza. But they were also excellent cooks and bakers anyway, so I don't know how much of the deliciousness was just their skill. GTers who own or have used pizza stones, is it a worthy investment? I want to make more homemade pizzas and it seems like it could up the quality of the pizza quite a bit. If you do like your pizza stone, any recs for which brands/types are the best?