From most important on down, in my not-so-humble opinion:
Book: Why We Get Fat: And What To Do About It by Gary Taubes. This brilliant 2010 book by science writer Gary Taubes is a follow-up to Taubes’s 2007 book Good Calories, Bad Calories (below), in which he argues that the modern diet’s inclusion of too many refined carbohydrates is a primary contributor to the obesity epidemic. He elaborates in Why We Get Fat on how we can change our diets, and why exactly we need to. Analyzing anthropological evidence and modern scientific literature, Taubes contends that the common “calories in, calories out” model of why we get fat is simply incorrect. Instead, Taubes promotes a low-carbohydrate diet, arguing that the consumption of carbohydrates drives the body to release insulin, which in turn can lead over time to insulin resistance and many other common ailments of the 20th and 21st centuries. Taubes also asserts that the consumption of carbohydrates leads the body to store excess energy in fat cells, but that reducing dietary intake of carbohydrates will result in the body being able to mobilize fat and will lead to weight loss. Read the Wikipedia entry or buy it on Amazon.
Book: Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health by Gary Taubes. This is packed with good science. This 2007 book argues that the last few decades of dietary advice promoting low-fat diets has been consistently incorrect. Taubes presents compelling evidence that carbohydrates, specifically refined carbohydrates like white flour, sugar, and starches -- and not dietary fat -- are the causes of obesity, diabetes, heart disease, and other ailments. Check out the Wikipedia entry or buy it on Amazon.
Website: Robb Wolf | The Paleo Solution book and podcast. Robb Wolf is pretty much the go-to guy for all things Paleo. He is one of the world’s leading experts on Paleolithic nutrition and author of the New York Times Best Selling book "The Paleo Solution: The Original Human Diet". He is also host of a weekly internet podcast called "The Paleo Solution", with Greg Everett (formerly Andy Deas). The podcast focuses mainly on Paleolithic nutrition, Paleolithic lifestyle and exercise. He is co-owner and coach at Norcal Strength and Conditioning in Chico, CA. He has an education and work background as a research biochemist and as an athlete. Do check out the podcasts -- they are packed with information, and free.
Website: Mark's Daily Apple. MDA is the premiere website for Primal. Since I am more Paleo than Primal (primarily because I am trying to avoid dairy), I use this website more as a resource than a bible, but it is packed with good information and discussions. Check out particularly his Definitive Guide to Grains, and In Defense of Meat-Eaters.
Web page: Why Maybe We're Really Not Meant to Eat Grains. (That webpage actually has a different title, but I invented a slightly friendlier one!) This is actually the first page that started to convince me that maybe grains were the devil. It certainly has a lot of interesting information.
Website: Whole9Life. This is a great Paleo resource site. Jump-start your new life with the no-nonsense 30-day challenge, Whole30. (And join the Whole30 community on Facebook.)
Website: NomNomPaleo. Great recipes. Check out her awesome list of Whole30 recipes (yes, a month's worth!).
Web Page: Whole9 Guide to Fruits and Vegetables (by season). So that you don't do what I did and go to Trader Joe's expecting them to have spaghetti squash in March.
There are also a bunch of links over there in the sidebar. -->