As a future teacher, finding websites with resources such as lesson plans, activities, and games is a top priority. Let's just say that I need as much help as I can get. The up side to this is that there are a ton of blogs, websites with free downloadables, and creative ideas out there. The down side is that it is an overwhelming information to sift through. As someone who is not very tech-savvy, I look for websites that are clean and easy to navigate, with information that is straight forward. As a (college math) class, we divided and conquered to see which websites we found useful to our future teacher needs.
The website I researched is called Math Forum, and it was a little less than helpful. While there was an excess of resources, the website was out-dated and extremely hard to navigate. There were links on links that I became lost in, with no home button at the top of the page to lead me back. The resources and information ranged from pre-k to graduate school, and with that large of a span, there is no way any one grade can include enough detail to be an effective resource. I do think that this website could be helpful if you knew it well enough to know exactly what to click on in order to find the information you need, but I just do not have that kind of time. There are countless other websites that have valuable information for teachers, that are convenient and easy enough to understand with first exposure. I personally just wouldn't visit Math Forum when I have infinite other resources at the click of a button that I know I can immediately understand.
I might recommend this website to researchers who want to compare lessons or standards among grades, but for teachers who already don't have enough time in the day, I really can't see this being an effective website.