You can sign the pledge and join the registry (primarily for professionals but categories such as "activist" and "writer" are also options).
You can also find resources such as organizations, websites/blogs, and books/media. If you join, you can add resources.
Linda has also written a book called Health at Every Size: The Surprising Truth About Your Weight. I haven't read very far in the book yet, and so far it looks like stuff that most fat activists already know, but it might be helpful to people who are on the fence about changing their health focus away from "losing weight."