There are many reasons to go plant-based, from health promotion/disease prevention, to environmental protection, to animal welfare. Listed below are some great resources detailing the various benefits of adopting a plant-centered diet, including tools to support you on your journey.
The Vegetarian Resource Group hosts a fabulous site offering nutrition information from some of my RD colleagues, recipes, and a guide to veg friendly restaurants.
This site has great tips for meal planning, recipes and dining out on a plant-based diet.
Position Paper of the Academy of Nutrition and Dietetics on Vegetarian Diets
Mercy For Animals and the Humane Society are very informative about the treatment of animals in the animal agriculture industry.