If you've seen the movie The Cube, apart from knowing that it's totally awesome, you might remember the part where one of the guys in the cube helped design it. He didn't know who he was working for, or what he was building though and just worked from a cubicle talking with people on the phone.
I once wrote a system like that. For about a month, I was in my cubicle, on the phone every day to a guy in another state who specified and tested my program. I've never seen him in my life. Pretty funny.
Actually, one day he did actually visit the office I was at, and stopped by my desk to say hello, but I wasn't there at the time (smoking, prolly :P). Since he was in the building for most of the day I probably actually *have* seen him, I just didn't know who he was. Which only makes it even weirder.