This site comes from a history teacher in Michigan, and has a free online world history textbook. It's visually interesting, and appealing to jr. high and high school level students. The site seems to be under development, and some links aren't working as of this writing. Definitely worth keeping an eye on this improving resource!
Tuesday Language Arts
This company provides books and activities for developing vocabulary.
This is a small mom-owned company that provides science resources.
Thursday History/Social Studies
This British site has resources for history learning at jr. high and high school levels.
Learn computer science through game design with this online visual programming platform.
Saturday Grab Bag
Printable curriculum materials for preschool through second grade levels.
This site gives instant, step by step solutions to math problems.