Hundreds of annotated links to great educational web resources for teachers and students
Mr. Nussbaum is the number one site on The Best Websites For Teaching & Learning About U.S. History, but it has really exceptional activities covering many subjects, including math, spelling, and science.
Online activities for K-12 + teachers
20 favorite e-lessons, with linked examples
Blue Web'n is an online library of 2194 outstanding Internet sites categorized by subject, grade level, and format (tools, references, lessons, hotlists, resources, tutorials, activities, projects). You can also browse by broad subject area (Content Areas) or specific sub-categories (Subject Area)
Lots of free lesson plans and resources for early grades - organized by subject
A collection of collaborative presentations which offer a large number of ideas for engaging lesson activities