Unix...man talk about some old school stuff. I used and still use Unix from time to time for my job.
It has often been told how the Bell Labs law department became the first non-research department to use Unix, displacing a newly acquired stand-alone word-processing system that fell short of the department's hopes because it couldn't number the lines on patent applications, as USPTO required. When Joe Ossanna heard of this, he told them about roff and promised to give it line-numbering capability the next day. They tried it and were hooked. Patent secretaries became remote members of the fellowship of the Unix lab. In due time the law department got its own machine.
Less well known is how Unix made it into the head office of AT&T. It seems that the CEO, Charlie Brown, did not like to be seen wearing glasses when he read speeches. Somehow his PR assistant learned of the CAT hototypesetter in the Unix lab and asked whether it might be possible to use it to produce scripts in large type. Of course it was. As connections to the top never hurt, the CEO's office was welcomed as another ouside user. The cost--occasionally having to develop film for the final copy of a speech--was not onerous.
Read all about it here. Pretty cool story.