Pottery. Sedimentary clays could be added to the raws as rocks, which could be used to make ceramics.
I've thought about that one myself. A previous poster has already outlined the basics. I do like the idea of bone porcelain, makes elves useful for more than just practice bolts.
Now optimally, you'd be able to set dwarves to gather clay, just like they gather sand. However, I don't think that's coming in the next version. Meanwhile, you can just turn all clays into sand as well, and tell users of your mod that it's an honour system, if your map only has sand, only make glass. If it only has clay, only make ceramics.
Next: I'd like to have the pottery workshop just make unfired pottery, which is then hauled to the kiln for firing. This depends on some wishful thinking on my part though. Namely, that we can specify in the new reactions, to preserve the quality of one of the reagents in the final product. That is, masterwork unfired clay mug + kiln = masterwork clay mug. Also, it relies on being able to add new reactions to the kiln, which is something I'm not sure will be in there.
Having the kiln right in the shop isn't really bad, per se, I just feel bad for the existing kiln. Being used for nothing but pearl ash must be a boring life
I thought the old buildings were going to be converted to the new system?
No, Toady has said that most, maybe even all, of the old buildings will remain hard coded. At least, as of 09/18/2009 that's what he said. Still unknown is if we can add custom reactions to the hard-coded buildings, or if it will remain limited to just the smelter, plus the new custom workshops. I'm eager to find out, though