Cybraryman.com This site has access to over 20,000 websites and is very thorough it is an excellent resource for all grade levels.
http://www.symbaloo.com/mix/4250-English-Homework-Help Get English homework help
Khanacademy.org This site is best known for math but is also good for science and has added art history. It contains videos for all levels.
Study smarter not harder: http://web.mit.edu/uaap/learning/teach/smarter/index.html
Math.com Get help with math at all levels even provides homework help
http://www.symbaloo.com/mix/4222-Chemistry--Science-Help Get Science homework help
Marcaria- Internet Resources on Citation
Spellingcity.com Great site for spelling and vocabulary primarily for elementary
Studyladder.com A comprehensive site of all disciplines and levels
Tenmarks.com This site is for math help grades 2-12
Wolframalpha.com This is a fact finding site, probably best for junior high/high school
Zui.com This is a safe search engine for kids plus it has a homework helper on the home page.
I will try to add to these each week.