WolframAlpha discussion on Education
came out last year as a computation engine, and I use it quite a bit to do quick mathematical calculations that my desktop's calculator feature just won't do. Like integrals.
The engine actually does a lot more than that, and they have some sample searches that show it's varied features. I noticed today that they have an education section on their discussion board
where people go to discuss the educational uses for such a tool:
The discussions are interesting, and include getting this tool in the hands of students via handhelds and what the implications are for testing and learning. This board might be a good place to keep an eye on in the future.