Happy Birthday, PGP!
Wow! 15 years! It seems like only yesterday that I discovered PGP and spent countless hours pouring over the documentation to learn all of the command-line options that were required to get things going. At the time, I was totally amazed at how few of my fellow computer geeks could get a handle on using PGP. After all, Windows wasn't really that popular until 95 came out. Almost everyone who used IBM-compatible PCs used DOS, or at least had to know how to use DOS in order to set up their menu program of choice.
One thing I remember doing, probably not in '91 but certainly not many years later, was setting up batch files to use with my mail reader of choice at the time, OLX, so that I could set it to use these batch files as an external editor in order to either sign or encrypt messages for posting on the local BBSs. I'm sure that if I dig around enough, I'll be able to find the 3 1/2 inch floppy that contains my original public and private keyrings. I even remember my original passphrase! Not only that, but I remember what I changed the passphrase to the first time I ever changed it.