This site has a collection of over 500 science lesson plans for grades 5 through 12. There is also a smaller selection of kid's experiments. There's a good search function, so you should be able to find what you're looking for, and all resources are free.
Online, interactive program for learning music reading and theory.
This non-profit organization offers over 100 free self-paced, online, college level courses.
This online math program is designed to help students with math problems (including dyscalculia.)
This hands-on grammar curriculum includes CD ROMs, teacher manuals, and games for learning gramma
Online, super-hero themed science games for elementary and middle school levels.
This program includes videos, worksheets and quizzes for history learning in jr.