Math and Science Resources
Kahn Academy focuses on multimedia learning geared toward teens. The videos lean mostly toward science and math tutorials, but include videos on topics such as history and civics, as well.
Interactives does what it says: provides interactive resources for growing brains, like yours and mine.There is a special focus on math and science resources, including statistics, ecology, meteorology, and chemistry.
Hippocampus provides multimedia tutorials on a variety of math, science and social science topics. Includes slideshows and videos, in case you missed something in class.
Webmath provides a variety of resources including quick look-ups for variables along with brief explanations at how they arrived at the answer. This site is for quicker information rather than in-depth lessons.