This thread just popped up in my feed but I'll throw my response out to the wind anyway.
Romertopf clay bakers. They simulate a brick oven-- awesome crusts and crumb, and the shape yields more of a regular loaf from looser dough.
Preheat the baker, sprinkle cornmeal in the bottom, drop the dough in, bake half the time with the lid on and the second half with it off.
To tell the truth, I've never been able to figure out any other use for a Romertopf in my kitchen. But if this is its one purpose in life, it rules