Recently I presented at the Association for Special Education Technology - Ontario Spring 2011 Conference about Assistive Technology for Math, with a focus on tools that are available for free to Ontario educators. I often get asked about what AT tools we can provide for our students who struggle with Mathematics. Unfortunately, there's no ONE tool that can do everything, so I've put together a collection of various tools and have indicated what strengths and needs match each tool. You can download my presentation slideshow and a handy reference chart that lists the tools by area of need. More related resources coming soon, so stay tuned. If you have your own favourite AT tools for Math, please share them in the comments.
UPDATE: A colleague just shared this site with me to add to the collection of virtual manipulatives sites. It's also free, and it's quite different from the others. It's one of the features in MathPlayground.com, called Thinking Blocks.