Toy Theater A plethora of interactive math tools and games. Teachers can navigate by skill at the bottom of the page. http://www.toytheater.com/math.php
National Library of Virtual Manipulatives Virtual manipulatives. No need to download "free trial," it is already there for use. http://nlvm.usu.edu/en/nav/vlibrary.html
Magic Pen Warning: Addictive! Using shapes and logic, this game challenges you (or your students) to make a ball move from one place to another. Site contains advertisements. http://magic.pen.fizzlebot.com/