The National Library of Virtual Manipulatives website is one of the best math tools available to teachers. The resources, lessons, and tools are amazing. I highly recommend browsing through the site. The web-based applets (small programs) cover all strands of math and can be used by all grade levels. I have tried just a small percentage of the tools and my students have loved using all of them. We especially enjoyed the lady bug mazes and challenging each other with the geoboard activities.
From their website:
"The National Library of Virtual Manipulatives (NLVM) is an NSF supported project that began in 1999 to develop a library of uniquely interactive, web-based virtual manipulatives or concept tutorials, mostly in the form of Java applets, for mathematics instruction (K-12 emphasis). The project includes dissemination and extensive internal and external evaluation."Visit the National Library of Virtual Manipulatives . (Say that three times fast!)
You also have access to customizable modules and tracking tools to meet the needs of your classes. Check it out and let me know what your class enjoyed working on.