Adventure Seeds: Fantastic Locations to Drop in Your Campaign
From the introduction:
This book isn’t a complete adventure. Instead it’s designed to give you the starting point for a great session. In the following pages you’ll find maps and descriptions of a new location, designed to fit easily into your campaign world. There are NPCs, rumours, background information, adventure hooks - in short, almost everything you need to build an awesome adventure in this location. The only thing you need to do is populate the dungeon with monsters and loot that fit your party and the story you want to tell, and you’re good to go.
The PDF adventure typically is distributed with twelve PNG files (high resolution maps, with and without grids).