I came across this site on an electronic music forum of things and was instantly taken by it, I did see it again at this year's EAHIL Conference. In a world where technology is doing more and more things for us and as a by-product making us feel that little bit more dumber, it was nice to come across a site that is so simple yet diverse in its offerings. That said, it potentially does a bit too much for us and certainly will be a life-saver for students and object of distrust from academics, especially those who increasingly see Wikipedia sneak into their classrooms and essays more often.
From what I've seen of it, it works really well and looks nice, you can work out everything calories to math formula to stocks and shares. The best way to understand it is to try it out for yourself - but below is Wolfram Alpha's own description if you want to hear about it from the wolf's mouth.
Wolfram|Alpha's long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. We aim to collect and curate all objective data; implement every known model, method, and algorithm; and make it possible to compute whatever can be computed about anything. Our goal is to build on the achievements of science and other systematizations of knowledge to provide a single source that can be relied on by everyone for definitive answers to factual queries.
Wolfram|Alpha aims to bring expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels. Our goal is to accept completely free-form input, and to serve as a knowledge engine that generates powerful results and presents them with maximum clarity.
Wolfram|Alpha is an ambitious, long-term intellectual endeavor that we intend will deliver increasing capabilities over the years and decades to come. With a world-class team and participation from top outside experts in countless fields, our goal is to create something that will stand as a major milestone of 21st century intellectual achievement. © Wolfram Alpha 2009