Emacs, Squeak, and Genera (Lisp machine OS) all qualify for me. It's no surprise that all of these examples are what I call "pervasively programmable": you can

Emacs, Squeak, and Genera (Lisp machine OS) all qualify for me. It's no surprise that all of these examples are what I call "pervasively programmable": you can not only extend them with code, but examine and modify the running system by typing code into it, shaping the system to your needs as it runs. Another pervasively programmable piece of enlightenmentware is Ashton-Tate Framework. It wasn't just a spreadsheet but a piece of "integrated software" (the 80s term for office suite), sporting spreadsheet, word processing, database, graphing, and serial communications capabilities, all under a unified desktop-GUI-like interface and programmable with the Lisp-like FRED language. If there were ever an "Emacs for business", it'd be Framework. It's pretty amazing that a program that powerful existed on 1980s PC hardware.