This wasn't a hack I did, but rather someone I worked for a long time ago told me about it (he actually did the hack).
It seems he worked for someone who was blind and who needed a way to read text files. So he figured out how to translate text files to braille and print them out using various characters such as . and :
The printers at the time were impact printers, so when a character was printed, the printing mechanism struck the paper hard enough to leave an impression that could be felt. Since the impression formed on the back of the paper, he had to print an inverted-backwards braille so that when the paper was turned around it was correct.
Of course, the act of reading eliminated the depressions so it was a read-once mechanism, but I always thought that was a pretty cool hack.
