I got this pottery trick at the Isaac Button workshop so many years ago!;-) To lift this jug off the wheel just put a clay 'button' over the mouth and lift. The button makes the jug airtight so it can be lifted without deforming the pot! This is probably one of those tools that goes missing from the historical or archeological record because it just gets chucked when it dries up and is easily replaced by a fresh one. But I'm neither a historian nor an archeologist, but I've got YouTube!
I'll hook you up with a link later when I'm at the computer.
[Ed: 2/26/11 finally getting around to linking up the video. A detail that I failed to mention was the special piece of wood used as a third point of contact when picking up the pot! look for it.]
[applause!!]