"Crockery Cookery" by Mable Hoffman was the first nationally recognized Crock-Pot cookbook. This book contains over 260 slow cooker recipes in every category from soups and stews to desserts and breads. Published in 1975, this book went a long way toward popularizing Crock-Pot cooking.
"Fix It and Forget It" by Dawn J. Ranck and Phyllis Pellman Good, was published in 2001. This is one of the largest and best known of the modern Crock-Pot cookbooks. This volume contains over 800 recipes in chapters covering basics to company dinners.
"The Weight Watchers Slow Good Cookbook" has over 160 WW-friendly Crock-Pot recipes. Each recipe has the nutrition and point value already figured out and posted for you. All recipes are low in fat and calories. This book is a perennial favorite for dieters and general slow cooker enthusiasts.
The sequel to the "Busy Woman's Cookbook," this Crock-Pot cookbook contains over 500 recipes for main dishes, appetizers, soups, meats and desserts, plus sections on turning your own favorite recipes into slow cooker recipes and ingredient substitutions.