From the introduction:
This document is intended as a reference guide to the City of Verbobonc. This is not an adventure in itself. Since Verbobonc is the only large city in this section of the Flanaess, and this area is a launching point for many adventures (Return to the Temple of Elemental Evil, etc), I foresaw the need for [player characters] to buy and sell magical or rare equipment, purchase spells, gather information, find a warm inn, etc.
This fan-made product was widely circulated among participants in the Living Greyhawk Verbobonc regional adventures. It is derived primarily from published sources but also presents some unique (non-canonical) materials.