Josh asked some great questions about yields and shrink this month. I recommend two books for more detailed information on standards. Francis Lynch has a new edition of his great reference tool
The Book of Yields: Accuracy in Food Costing and Purchasing
and I prefer the paperback book over the CD.
Mary Molt's classic catering book
Food for Fifty (12th Edition)
has excellent yield and standard portion information.
You can also get yield information on meat from the must have industry standard. The NAMP's
The Meat Buyers Guide : Meat, Lamb, Veal, Pork and Poultry
has zero fluff. I love the tables at the beginning of each section.