Man, I don't know why I haven't looked in this thread before. I used to be a baker at a small artisan bakery, still do a few loaves a week for myself, and pizza every week or two. I use a sourdough starter that I started about 8 years ago, it keeps getting better.
Last batch (saturday) was an old favorite, potato bread with fennel seed.
Anyway, I use a kiln shelf (for pottery) for a baking stone. They tend to be thicker than most pizza stones, and granite or soapstone can transfer heat too fast if you have your oven hot, and will burn the bottom of the bread.