SBC Knowledge Network Explorer : Online Learning : Blue Web'n Homepage This is a nice collection of education sites divided into categories. They even assign web sites Dewey numbers!
From the site:
"Blue Web'n is an online library of 1800+ outstanding Internet sites categorized by subject, grade level, and format (lessons, activities, projects, resources, references, & tools). You can search by grade level (Refined Search), broad subject area (Content Areas), or specific sub-categories (Subject Area). Each week 5 new sites are added. You can get a list and description of these additions sent to you by signing up below for free weekly updates!"