Thinking Mathematics is an uncluttered and joyous approach to school mathematics from middle school, high school, and beyond. The site is based on the material that appears in the book series Thinking Mathematics!
There are excellent newsletters that I have signed up for that gives out great resources and extra examples you may be going through with your own students. Here is May's Newsletter: http://www.jamestanton.com/wp-content/uploads/2012/03/Cool-Math-Newsletter_May2012.pdf
There are links like a School Math Genius: Five Principles. A Teacher's Guide. Here is the first one from YouTube.
Here is a link to his page of his five principles: http://www.jamestanton.com/?p=1097
There are also thinking puzzles and cool math videos that make students think and problem solve.