In no particular order:
Resources for Catholic Educators	Lesson plans, clipart, magazines, Saint of the Day, etc.
LessonPlansPage.com	Over 2,000 free lessons!
A-Z Teachers Stuff	Themes, Lessons, Tips, Articles, etc.
First School	Fun preschool lesson plans, educational early childhood activities, printable crafts, printable activities, calendar of events and other resources for children of preschool age.
edHelper.com	Lesson Plans - Worksheets for Primary Teachers, Math, Writing, Reading, Science, Technology, Social Studies, etc.
RHL School	Your place to get an enormous supply of free quality worksheets for teaching, reinforcement, and review.
ShapeBooks.com	A place for teachers, parents, student and children to create, learn and have fun writing!
abcTeach	This is the place for kids, parents, student teachers, and teachers.
Teachers.net	The ultimate teachers resource.
SchoolExpress	Lesson Plans - Worksheets for Primary Teachers, Math, Writing, Reading, Science, Technology, Social Studies, etc.
States and Capitals	Says it all.