Years ago we were working on the first PC-based phone gateway, which allowed you to use your phone line and computer as a call gateway over IP.

A guy called up because he wanted our linux drivers.

We didn't have any linux drivers.

So he called back a while later and said "Here I wrote the linux drivers for you."

He had reverse engineered the board and wrote the drivers to make it run on linux based on all the specs of the various chips on the board.

We hired him on the spot.