HyperCard

Unique-but-abandoned Mac-only product, developed by Bill Atkinson (following an LSD trip). Could be a HyperText engine (Beyond Cyberpunk), could be a (mainly single-user) data-backed GUI CardDeck-based development environment. Launched 1987.

Goals/design, from interview linked above

help people from different areas (physicists, musicians) communicate with each other
through an interactive medium
so it was effectively a software construction kit

Why was it killed? (from same interview)

meta: note that iBooks-Author is kinda its descendant
Apple was having financial troubles, had to kill some projects
HyperCard "had some of that Sculley stink on it" (from Jobs' perspective)
Apple was afraid of pissing off indie developers with people building their own apps (end-user programming) - or maybe Jobs didn't care about e-u-p either

Dan Shafer wrote some books about it.

See MetaCard for a close clone, or PythonCard for something similar but a bit different.

Bill Seitz