The America's Test Kitchen Family Baking Book I'm a big fan of ATK. I don't always agree with their assumptions, but they're recipes are always well tested. A good place to begin any recipe research.
James Beard's American Cookery
JOY OF COOKING This was a gift, and a welcome one. I use the 1975 edition, but I would trust the 2006 edition. Again, an important source for traditional American cooking.
Baking with Julia: Savor the Joys of Baking with America's Best Bakers I love this book, and it's quite cheap now. I don't necessarily love the butter cake recipes, but the Lemon Loaf is a go-to cake for me. It us also very strong on pastries and breads. If you cook through the book, it's a great education.
The Quick Recipe Since I bought the Ring bound ATK series, this is one of the only single-subject ATK books I kept. This is the original source of the Best Pumpkin Muffins Ever and No-Bake Cheesecake. It has several more quick and very yummy baking recipes.
I make a very small amount of money if you buy the books through these links, but don't feel pressured.