These sites are all free to use, but may require you to sign up for a membership, which is also free. It only takes a minute and usually allows you to save information that you would like to be able to find easily again.

Shmoop:  http://www.shmoop.com

Shmoop is great for homework help in Literature, US History, and Poetry. They even have a feature that will help you organize your thought for that big essay or paper.

InfoPlease:  http://www.infoplease.com/homework/

InfoPlease has available homework help on Geography, History, Language Arts, Mathematics, Science and Social Studies.  They also offer help with Writing, Research, Speaking & Listening skills, and Study skills.

Discovery Education:    http://school.discoveryeducation.com/homeworkhelp/homework_help_home.html

Discovery has homework help for most subjects and most levels. They include many videos and many other links to sites of interest.