Romertopf

I have three second hand rommertopf bakers, use them all the time. I wouldn't recomend roasting other things in them, especially with fats.  Fat residue will  smoke when you preheat the rommertopf later on to bread baking temperatures. I don't season mine at all, just heat them up and put dough on an oval piece of parchment in them. Lower hydration doughs are easier to handle, I have to admit. 

I have an old unglazed one.  I haven't used it for anything other than bread.  I followed instructions (not sure if they were official or not, I can't find the instruction booklet) which were to soak the bottom, then pat it dry, coat the inside/bottom with oil and then cornmeal (medium works best I think, or polenta), then add the dough.  You can use the 'topf for just the bake or the final proofing also I think.  The instructions are to put it in a cold oven and turn the heat up.  I assume a cold oven is needed to avoid the possiblility of cracking, I have used a slightly warmed oven with no ill effect.  It worked well, the loaf didn't stick and the bottom washed up nicely with no oil or charred residues.

I haven't used it for anything other than bread, I guess this might result in interesting flavours.