Cobs, of course, need you ask
But also, I've been buying and finishing some unfinished briars and clays from this guy on the bay of e:
fory63 | eBay
I've documented some of them on this thread:
www.cigarbum.com/forum/the-do-it-yourselfer-discussion/sandblasted-briar-5180.html
They're pretty thin and rife with fills, but smoke just fine although the bowls can get a little hot. Nice thing about their thinness - very lightweight, easy to just hold in your mouth while working with your hands.