Shannon: I'm crazy about old cookbooks. Kettner's Book of the Table is a favorite, but most prized are the Victory Cookbook and Rumford cookbooks given to me by my father, who wanted me to have the cookbooks used by my grandmothers on both sides of the family.
ann: my favorite vintage cookbook i ever found is called "To The Queen's Taste" written by Helen Train Hilles.
Rich Simon: For NY'ers, don't forget about Kitchen Arts & Letters on 93rd Street. Unbelievable collection, lots of old stuff.
Librarian: For really old online cookbooks, check out "Feeding America: The Historic American Cookbook Project"