Am I the last person on the block to come across Microsoft Mathematics? I downloaded it (which is now free, it seems) and tried it out this week.
Here is a brief description from the "About" notes:
Microsoft Mathematics provides a set of mathematical tools that help students get school work done quickly and easily. With Microsoft Mathematics, students can learn to solve equations step-by-step, while gaining a better understanding of fundamental concepts in pre-algebra, algebra, trigonometry, physics, chemistry, and calculus.
Microsoft Mathematics includes a full-featured graphing calculator that’s designed to work just like a handheld calculator. Additional math tools help you evaluate triangles, convert from one system of units to another, and solve systems of equations.
It seems to have several nice features that kids at the 9-12 level would enjoy. I noticed right off that some of my kids studying trig would love the fact that it has an inverse function for the secant, cosecant, and cotangent that works in degrees, radians and the almost extinct, gradians (more commonly called grads). If you don't know what grads are read here.
It also has several computer algebra skills, indefinite integrals, expansion of powers of an expression (for students, it will raise (x+y)^5 and expand it), and of course factoring. It works in real and complex numbers, graphs in 2d and 3d with input in Cartesian, of polar form (and you can enter implicit relations..
The matrix input allows up to 15x15, and the linear algebra keys include dot(inner) and cross products and will row reduce a matrix (yes it does inverses, but you don't HAVE to use it).
It will solve equations or do integrals and then show and explain the steps.
I expect that many students will abuse this as they do other technologies available to them, but the student who really wants to learn math can use this as a valuable resource.
There is also an add-in for Word.