I have a zillion cookbooks but the two I use the most are:
The Practical Encyclopedia of Baking- I think there is a recipe for any baked good you can imagine.
http://www.amazon.com/Practical-Ency.../dp/B0006924X6
Better Homes & Gardens New Cookbook
http://www.amazon.com/Practical-Ency.../dp/B0006924X6
What I like about the BH&G one is that it contains all the information about how long to cook a roast/chicken/etc. without a set recipe, has tips on cooking techniques for things like pie crust, and is all about the basics, really.
Specialty cookbooks are fun, like I have one that is all potato dishes and I have crock pot cookbooks, Southern Living cookbooks and .. shoot, all kinds of cookbooks, but I consult these two general, every day type cookbooks most often because they aren't just about recipes, they include information about techniques.
allrecipes.com is where I go for most recipes these days, honestly. I have an old favorite called Brand Name Recipes that is full of recipes that come on product containers.. like Hershey's cocoa, Bisquick, etc.