In past reviews, I have recommended web sites for professional organizations, such as NCTM and the Washington State Mathematics Council. It is time that I also recommend the web site of the Oregon Council of Teachers of Mathematics, as their people and their products have had a big impact on me and my teaching.
First, consult their Publications page, as I highly recommend that you get a copy of their problem solving books (especially the ones at the Intermediate and Secondary levels). Over my teaching career, I have used a great many of their problems with my students...with good success. If you find these books helpful, you might also try their book Puzzle of the Month & Math Magic, which is a compilation of a series of articles published in their journal.
If these books prove valuable to you, I suggest you join the OCTM...so that you can get a subscription to their Oregon Mathematics Teacher, which has six issues each year. This journal is written by teachers for teachers, and has maintained high-quality through the years....I think I have been using it as a teaching resource for more than 35 years now.
Next, you might glance at OCTM's front page, as it has some materials (talks, position papers, links) that are of interest to mathematics teachers beyond the Oregon area. One thing I especially like is the fact that OCTM supports all of Oregon's first-year mathematics teachers with a free subscription.
Finally, the OCTM site offers links to other quality web sites in the areas of Calculators and Computers, Mathematics Assessment, Mathematics Education, Mathematics Resources, Mathematics/Science, Mathematics Sites for Kids, General Mathematics Topics, Problem Solving, Statistics, Teacher Education, and TIMSS Reports. Plus, you might visit the OCTM website regularly just to access their section "Links of the Month." For example, that is how I found out about Jim Reed and the Argyll Center ...three years ago.