Every chef I know has a huge cookbook collection. My wife and I have hundreds on every subject, from small plates to dessert. I like shopping for cookbooks the way most women like shopping for clothes; you can never have enough.
My two favorites are Thomas Keller’s French Laundry & Charlie Trotter’s Wild Game. These two have lots of great recipes, but what I like most are all the great ideas. I usually do not use the recipes in the book. The ideas and flavor combinations are what make these cookbooks valuable. I use cookbooks more for reference on combinations and flavor profiles than anything else. I take a sauce form here, put it with a starch from there, with a protein from elsewhere, and a new plate is born.
A whole dish came to be one time because of an article I read in a magazine.
I also feel it is essential for chefs and cooks to own and read as many cooking magazines as possible. I think it is important to stay current on what is happening around the globe and magazines are the best source. Publications such as Cooking Light, Food Arts, and Great Taste provide information to improve your cooking. Today with iPads, BlackBerries, and Kindles, there is no excuse not to read magazines. They can all be accessed online and taken wherever you go. The more you read the more you learn; the more you learn, the better chef you become.