SimpleK12 is a great site that has a tremendous amount of resources for educators. They offer online professional development, curriculum resources, assessment ideas, free downloads and resource kits and resources through their blog, I Love EdTech.
SimpleK12 is also know for their bunny slippers! They promote their online offerings as a way to learn while in your pajamas and the bunny slippers have become their symbol. I was chatting with some of the SimpleK12 staff at ISTE2011 and they were all wearing their bunny slippers.