Disney attractions that never were

Wikipedia has this entry showing various parks, lands and attractions that were in planning stages through the years, but never made it into existence for various reasons.

Theme parks that were being planned include Disney Sea at Long Beach and Disney Niagara Falls.

Lands at Disneyland that never happened include...

Liliputian Land

A land that was to be located north of Tomorrowland east of Fantasyland. Everything would have been constructed on a greatly reduced scale.

 Big City Land

A New York-themed area where Mickey's Toontown now sits; it was to have featured a big Broadway-style theater that presented live stage shows every day. This idea became the inspiration for the American Waterfront at Tokyo DisneySea.

At EPCOT there were plans at one time to add Iran and Israel pavillions. Then there was the Soviet Union pavillion...

Planned in the early 1990s, this would have been placed between China and Germany and dominated by a recreation of Red Square. The center building would have housed a sled-like ride showing the Russian landscape based on Russian folk tales. There also would have been a unique show blending film, Audio-Animatronics and a live actor that would showcase Russian history.
It reached the final stages of approval but was later cancelled due to the dissolution of the Soviet Union.

 Also at EPCOT, in the Japan pavillion, there might have been the Godzilla Bullet Train ride...

Similar to both the Mt. Fuji and Bullet Train ideas, in this case having the bullet train run afoul of Godzilla in Tokyo Bay, followed by a race to safety. This ride was planned for the Japan Pavilion at Epcot.

Animal Kingdom might have had the Tree of Life Carousel...

Instead of The Tree of Life, this double-decker carousel would have been the park's iconic symbol. Guests would ride on a Dumbo-like ride on vehicles based on animals from around the world.

The article has a long list of such things and makes for interesting reading.