Since it's the slow time, I figured I'd give a shameless plug for a fairly new project (in a similar topic as NELSAP):
A cancelled ski area is defined as an alpine ski area that was proposed and/or partially constructed but never opened.
I don't think we have every area, but I do think we're pretty closed.
Some particularly interesting ones include:
Bigelow Mountain - Maine - was part of Maine's 1976 Winter Olympic bid
Dorset Hollow - Vermont - would have been the largest ski area in New England
Willard Basin - New Hampshire - also would have been the largest ski area in New England (tram, gondola, monorail)
Greylock Glen - Massachusetts - partially built in the 1970s