on the topic of clay instruments, i have to say that one of the most interesting clay instrument makers actively making and promoting clay instruments is barry hall. you can see barry's work on his site burntearth. barry is also the creator and moderator of a yahoo group dedicated to the creation of ceramic musical instruments. on the links page there, you will find links to some of the members websites. i am really facinated by the range of possibilities in making instruments out of clay, and barry is very creative with some of the new types of instruments that he is making.
in my personal collection of clay instruments i just acquired a new udo and i am getting acquainted with it. i also own a clay flute called the "tlapitzalli" created by guilliarmo martinez (from southern california). this flute is a reproduction of a mayan temple flute and i own one of the last flutes that gulliarmo made out of white hopi clay. guilliarmo doesn't maintain a website, but you can see and buy his work from the oregon flute store.