National Library of Virtual Manipulatives: http://nlvm.usu.edu/en/nav/vlibrary.html
NCTM Illuminations Website (Activities, Lessons, Web Links): http://illuminations.nctm.org/
Interactive Activities: http://www.shodor.org/interactivate/activities/
Math 10 Consumer Math Project: http://homepage.usask.ca/~drb149/index.html
When you come across other good math websites, please email me and I will share them with other teachers through the blog. Thanks!