I stumbled upon this cool site a few days ago. http://mathwire.blogspot.com/
It is the blog associated with the website. http://www.mathwire.com/
They are both filled with terrific math activities. The blog however highlights a timely item available on the website. Which is helpful since mathwire is jampacked full of activities and I for one find it very overwhelming to weed through!
Check them both out!