Years ago, I met a Japanese professor who eventually became my adviser during my one and a half year stay in Japan. CRICED, the institute he was working also develops mathematics software in elementary and secondary schools. Below are 5 of the math software that they have developed.
1.) Grapes – a graphing software that allows users to draw most functions discussed in the secondary curriculum.
2.) Geometric Constructor – a dynamic geometry software for teaching and learning geometry. Allows users to publish contents on the web.
3.) DbookPro – a tool for developing digital textbook. This can be done by scanning textbooks and or importing textbooks images. I have written two manuals of dbook (basic and advanced) and you can view the sample output of a dbook here. You can download dbookPro here.
4.) Geometry Construction Language (GCL) Editor – an xml-based software used for creating educational materials in Flash.
5.) DGraph – Used for making and editing graphs from data and equation.
I have only tried 2 of these software (dbookPro and Grapes), but you might want to explore all of them.