Yesterland provides a look at discontinued Disney Attractions, with links to a variety of forums related to Disney topics.
WDWMAGIC - Unofficial Walt Disney World discussion forums
Includes discussions about Walt Disney and all things related to the Disney empire.
D23: The Official Disney Fan Club
Named in honor of the year 1923, when Walt left Kansas City, headed for Hollywood and founded what would become the Disney Studios.
Walt Disney Birthplace Restoration Project
Library of Congress Collections (contain Disney-related materials in multiple formats)
Duke University Outdoor Advertising (contains images of Disney billboards)