Some great sites for Nutrition information:
These are the ones I use for my own knowledge as well as buying and reading books.
Empower. Although I don't support the use of low carb "manufactured goods", (I prefer whole natural foods) they host a great forum with a wonderful, caring, knowledgable and supportive community. Sign up (free) and say hello.
Jimmy Moore has achieved some amazing things Livin' his "La Vida Low-Carb". Have a read of his blog. There are some eye-opening articles here and he has been a great source of information and inspiration to me personally. (Before Livin' La Vida Low Carb and after)
Protein Power.The website that supports the "Protein Power" and "Protein Power Life Plan" books, both available from Amazon. It's The Official Web Site of Drs. Michael and Mary Dan Eades, partners in life and in writing the two books just mentioned. The site also hosts blogs by Dr. Mike and Dr. Mary Dan and also a chat forum as well.
The Omnivore is another excellent site for Paleolithic consumers. It is written by Anthony Colpo and he has just released his 1st book.
Amazon have some good books for Nutritional Information. As well as PP and PPLP I have also bought "The Paleo Diet" by Loren Cordain, "Neanderthin : Eat Like a Caveman to Achieve a Lean, Strong, Healthy Body", by Ray Audette and
The Covenant of the Wild: Why Animals Choose Domestication by Stephen Budiansky.