I stumbled across Discovery Education which has a ton of resources for various subjects including math. According to their banner in my NCTM daily e-mail, they are getting ready to unveil a digital textbook that is made for the 21st century student. As I explored the math resources for grades 9 to 12, I found a lesson plan that has students researching various proofs of the Pythagorean theorem and then making a poster on the material. I think they could also make an infographic or a presentation. There are lots of possibilities.
In addition I found quite a few matching vocabulary sheets, brain boosters or word problems, and a couple resources to help students learn material on their own. This is wonderful having more resources available.
This site also has materials for grades k to 8, puzzlemaker, lesson plans and it has resources for both parents and students. I have bookmarked this page for my personal bookmarks so I can use these in the classroom.