From Scholastic, this website offers several graphic organizers to aid with reading comprehensions. Organizers include: reading, story elements, plot, sequence, assessment, character analysis, and setting.
This is another site that provides labeled diagrams with explanations that can accompany lectures/presentations. The diagrams are also accompanied by legends to describe any symbols. Another great resource!
On this website, you use graphics to create a story. The options are a little limited, but it could help in generating ideas for creative writing. Although this website may seem a little juvenile at first glance, it is actually very fun and I think high schoolers may enjoy it.
this site provides interactive graphs and geometric shapes that students can maniulate and observe properties. there are also concept quizzes with each graphic.
Dozens of calculus applets that cover everything from continuity to series and sequences. Good way to give students another perspective to look at calculus graphically. These applets let you change the numbers to see how the graph changes.