Illuminations - activities by National Council of Teachers of Mathematics. There are loads of great activities that are mathematically sound. These activities range from kindergarten to complex high school level mathematics.
Xtramath - This is a great online resource for working on your math facts. Parents can set up a free account. Daily use will show a difference.
2Pi Productions - Check out the amazing math rap videos by teacher Jake Scott (2Pi) below.
Click here for the NPR story about him.
Click here for the NPR story about him.