YouCubed website, Stanford U
Contains a variety of resources about the latest thinking about teaching and learning of mathematics. Example: videos on brain science about how we learn math, as well as articles for parents and teachers, and tasks for students.
This site contains articles and resources for parents and teachers regarding ADD/ADHD.
This site contains a myriad of resources (articles, blogs, parent supports) addressing the gamut of learning issues. If you register, supports can be tailored to your child's individual needs (ex. just focus on ADD, or dyslexia, or organization). Check out "Through Your Child's Eyes" to get a sense of what your child's particular issues might feel like for your child.