Diet Freebie

Dr. John Berardi, author of the Seven Basic Habits, has a freebie PDF up for his Precision Nutrition System.

The whole system is like $97+shipping, but this book is free. While the information is pretty basic, it's sound and it's got a lot to recommend it.

Precision Nutrition Strategies

You may have to join their free forums to access this, but both the forums and the book are free.