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

Mugs
Cinderelish
Northern Clay Center

Ceramic Artists List
Jonathan Mess: http://www.artmess.net (Really unique work)

Ceramic Arts Daily: http://ceramicartsdaily.org/

Watershed Ceramics: http://www.watershedceramics.org/links.php
Maine Crafts Association: http://www.mainecrafts.org/members/membersearch.aspx This link doesn't seem to be helpful, but the organization exists...
Maine Potters’ Market: http://www.mainepottersmarket.com/mpm.htm
Maine Craft Guild: http://www.mainecraftsguild.com/Clay.html
More Links!

Museums with great Ceramics/Pottery Collections
http://www.metmuseum.org/
A more specific MET site: when here, scroll down to Ceramics and choose your culture: http://www.metmuseum.org/toah/hi/c.htm
http://www.vam.ac.uk/Type in the content of your page here.
British Museum: http://www.britishmuseum.org/default.aspx
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.