WolframAlpha is new. It was launched on May 15. It's a search engine but much more. All subject area teachers will want to try this one.
Wolfram|Alpha is the first step in an ambitious, long-term project to make all systematic knowledge immediately computable by anyone. You enter your question or calculation, and Wolfram|Alpha uses its built-in algorithms and growing collection of data to compute the answer.
http://www.wolframalpha.com/index.html
