[ozten]

Sketchpad by Ivan Sutherland in 1963, would be one.

It allows one to draw CAD drawings, convert drawn letters into labels, etc in a more natural way.

https://en.wikipedia.org/wiki/Sketchpad

[jecel]

Besides the Sketchpad, Alan always mentions Grail (GRAphic Input Language), designed by Thomas Ellis and programmed by Gabriel Groner and others at the Rand Corporation. That was from 1964.

As far as I know, Alan also greatly admires the work done at MIT in the 1970s like http://www.paulmckevitt.com/cre333/papers/putthatthere.pdf