Microsoft Mathematics provides a graphing calculator that plots in 2D and 3D, step-by-step equation solving, and useful tools to help students with math and science studies.
Microsoft Mathematics is now available for free
Among others, Microsoft Mathematics has the following tools:
Equation Solver. Provides step-by-step solutions to solve equations.
Triangle Solver which can be used to investigate and solve problems about triangles.
Unit Converter which converts measurements from one unit to another.
Grapher which can plot 2d or 3d graphs in the Cartesian plane/space
Ink Handwriting Support, which supports handwriting for Tablet PCs.
service that allows users to create charts and graphs of statistics from the NBA, NCAA Basketball, the NFL, NCAA Football, and NASCAR. Users select the data sets that they would like to compare and StatPlot creates a chart of that data
a fascinating discussion on the Mathematics of War. When your students ask where they'll use math in real life, have this video handy. Here's how the video is described on the Ted site: "By pulling raw data from the news and plotting it onto a graph, Sean Gourley and his team have come up with a stunning conclusion about the nature of modern war -- and perhaps a model for resolving conflicts."