Wolfram+Alpha

"Wolfram Alpha introduces a fundamentally new way to get knowledge and answers— not by searching the web, but by doing dynamic computations based on a vast collection of built-in data, algorithms, and methods."

Wolfram Alpha is built on Wolfram's earlier flagship product, [|Mathematica], a complete functional-programming package which encompasses computer algebra, symbolic and numerical computation, visualization, and statistics capabilities. With Mathematica running in the background, it is suited to answer mathematical questions. The answer usually presents a human-readable solution. Alpha also incorporates elements of webMathematica in delivering its content. Wolfram is not a search engine in the strict sense of the word, it's a computational knowledge engine: it generates computations from its own internal knowledge base, instead of searching the web and returning links. In simple terms it is a very powerful calculator with an attractive user interface.