A handy (and official) random encounter generator for Advanced Dungeons & Dragons circa the late 80s. These made for a nice set of tools when combined with the Character & Treasure generator in Volume II. My own DM still makes use of the Assistants today as our player party ventures across the map of Oerth (Greyhawk).
Watch your own players quake as the Assistant casually tosses out 109 Drow with which to contend. Then see your campaign transform into the Great Escape as your players are carted off to the Underdark to be traded in the harrowing slave markets of Erelhei-Cinlu!
If GOG helped the community preserve these creation tools for modern systems, the community might be in a better position to expand and perfect them!