Lesson Plans, etc

http://www.sciencenetlinks.com/matrix.cfm

http://www.thinkfinity.org/MPSearch/Basic_Search.asp

Open Educational Resources Archive
http://www.archive.org/details/education

The Open Educational Resources Archive is a collection of educational content including coursework, study guides, exercises, and recorded lectures. It is meant for students, teachers, and self-learners at all levels.

Online Lessons to prepare for AP Exams
http://www.archive.org/details/ap_courses

Open University (United Kingdom) 

http://www.open2.net/home.html

Reith Lectures

http://www.bbc.co.uk/radio4/reith/

BBC Schools

http://www.bbc.co.uk/schools/

Discovery Channel Education

http://school.discovery.com/

United Streaming

http://www.unitedstreaming.com/

Incredible Art Lessons

http://www.princetonol.com/groups/iad/lessons/lessons.html

Core Knowledge Foundation (E. D. Hirsch)

http://www.coreknowledge.org/CK/resrcs/lessons/index.htm

Math Worksheet generators/collections

http://themathworksheetsite.com/

http://www.superkids.com/aweb/tools/math/index.shtml

http://www.kutasoftware.com/free.html

http://www.mathsonline.co.uk/nonmembers/gamesroom/transform/transform.html

http://www.mathworksheetsonline.com/siteblog/weblog/