Math Education Groups
The National Council of Teachers of Mathematics is the premiere professional organization for math teachers. Their web site includes sections on classroom resources, standards, research and professional development.
The Association of Mathematics Teacher Educators (AMTE) has a range of publications available on their web site, most available for free.
AMTE is devoted to the improvement of mathematics teacher education, with over 1,000 members devoted to the preservice education and professional development of K-12 teachers of mathematics.
Research in Mathematics Education is a special interest group of the American Educational Research Association. Their site includes a resource links section.
The California Online Mathematics Education Times (COMET) is an electronic publication featuring STEM education news from California and across the nation, as well as information about professional events and opportunities, current educational issues, and online resources.
The selection and implementation of national standards in mathematics are on many folks' front burner. Controversy swirls around various poles of thought of what they should be. Standards go hand-in-hand with teaching methods in math education more than in most other subject specialties.
The thing is that various methods work for various purposes with different students and no one can untangle all the variables to arrive at a consensus. The only sensible solution for teachers is to strike a balance, because it is easier for young folks to learn math than older folks. That we do know.