Toronto's Steve Munro has an interesting post about a possible expansion of Toronto's subway/rapid transit system that never happened.
There's plenty of text and images at Munro's site.
Back in October 1974, the TTC was considering various proposals for new rapid transit lines, one of which was the Queen Street subway. This line would have run from Roncesvalles and Queen east to somewhere beyond Broadview, then turned north past Greenwood yard and continued via Donlands to O’Connor. At that point, the line would cross the Don River to serve Thorncliffe and Flemingdon Parks winding up at the CPR crossing north of Eglinton.
There's plenty of text and images at Munro's site.