At the cafe, we have a resource library that we use for both unusual catering requests and standard cooking issues. I picked up Baking Illustrated: The Practical Kitchen Companion for the Home Baker as something to look through during a short break, and now it's my new favorite baking resource book. The people of Cook's Illustrated have put together a collection of their best baking recipes (which is nice) along with a brief, and sometimes not so brief, synopsis of why that recipe works better than other variations (which is even nicer). I don't always use the recipes out of the book, but I do read up on it before working on new recipes. This is because the book tells you not only what does and does not work–but also WHY it does or does not work. This is what makes Baking Illustrated an important book for people who like to tinker with recipes.
Sadly, I don't own this book yet. Amazon.com has it for about $11 less than the bookstore, but MacDaddy won't let me buy it until I sell some more stuff on ebay. I guess I need to start rummaging through my geek collection and find something else to let loose.