WolframAlpha is an amazing third-generation search engine that can tell you almost anything about anything: math, chemistry, socioeconomics, geography, etc. You can input a formula, or just a few words as a question, and Wolfram will make the appropriate assumptions about what you want to know. Especially good with relational data, e.g., what's the ratio of France's GDP to Italy's?
The screencast illustrates a few of the many ways this tool can be useful: http://www.wolframalpha.com/screencast/introducingwolframalpha.html
This should be an excellent classroom tool, both in content-based projects and math work, and for general English, writing research papers, making predictions, etc.