I was flicking through some old Amiga Shopper magazines the other day, and saw an interesting PD program called "Liner". This looked a surprisingly modern program, the kind of thing that would have netizens frothing because of over-hyped productivity gains, for just a low-cost monthly subscription and 30 email newsletters a day.
Basically, this was a freeform word processor, where you could create very quick tabulated lists - essentially a tabulated list form of a tree data structure. Ideal for quick project planning - breaking down a project into tasks and subtasks etc.
Liner was the PD program. They referenced a commercial more-polished equivalent called Flow.
Cripes. Flow. That would have been a mult-million webpage if only they weren't 30 years too ahead of their time!