Note: Please read "Word to the Wise" in the sidebar on the right, before reading this post.
A forum moderated by Mary Shomon. Full of informative articles, discussion groups, links to information, understanding lab values, and guidance on talking with physicians. Some of the information needs updating, check the dates on each article as some of it is older. Still, it's probably the most comprehensive layman's site anywhere, and has the best assortment of information pertaining to all aspects of living with thyroid disease.
Books: A little outdated but still helpful.
Living Well with Autoimmune Disease by Mary Shomon Since many people with one autoimmune disorder can have several other autoimmune conditions at the same time, this is a good book to raise awareness of some general health considerations.
Living Well with Hypothyroidism by Mary Shomon Specific to hypothyroidism. Has a lot of good information about Hashimoto's, explains lab tests related to thyroid, dealing with physicians, and relieving symptoms. Some of the nutrition information is outdated.
The Thyroid Solution by Ridha Arem, M.D. (This one was helpful to me in that it supported the use of T3 replacement. Some good general health guidelines, but unfortunately it is written in the "this is the miracle cure" style which I don't agree with. Not everyone is going to benefit from Arem's approach. Yes, Cytomel was a great thing for me but I know it doesn't work for everyone.)