Tim Mott and Larry Tesler developed the desktop metaphor at Xerox parc back in the 70s. I don’t think it’s an overstatement to say that it’s probably one of the most significant developments in interaction design in the past 50 years.
What’s fascinating is the way they did it. The desktop metaphor didn’t come about through a flash of genius inspiration - instead they developed a research method that basically enabled the end users to invent it themselves. As Tim describes it:
“The way we went about the design was to actually work with the editors [i.e. end-users], Atkin. I went back and spent several weeks with them, and put them in front of an imaginary display with a real keyboard and a real mouse, and asked them if they could sort of walk me through imagining using that hardware to edit. Once Larry and I hit on this idea of having people talk about how they would want to do the work they did today, but with a new set of tools, the design itself became pretty simple as well, because it was a methodology that came out of it.”
This clip is from the DVD that comes with Bill Moggridge’s book “Designing Interactions”. On the book site you can find this and loads of other great interviews (looks like the site is currently down, though Ammendment - it’s back up now).
