Here are some sites you might visit to find cool clay:

Northern Clay Center

Ceramic Artists List
Jonathan Mess: (Really unique work)

Ceramic Arts Daily:

Watershed Ceramics:
Maine Crafts Association: This link doesn't seem to be helpful, but the organization exists...
Maine Potters’ Market:
Maine Craft Guild:
More Links!

Museums with great Ceramics/Pottery Collections
A more specific MET site: when here, scroll down to Ceramics and choose your culture: in the content of your page here.
British Museum:
Pacific Asia Museum

Pinch Work:
River Valley Crafts A woman in New York who pinches a lot of forms.

Slab Work:
Margaret Bohls
Hayne Bayless
Cynthia Guajardo
Cuong Ta -- slab forms that deal with line and the interaction between positive and negative shapes.