Wolfram Alpha Computational Knowledge Engine
Wolfram|Alpha is a new service on the web that calls itself a “computational knowledge engine.” Ask Wolfram|Alpha a question, and it produces results by doing computations from its internal knowledge base. It does not search the web or return lists of links. The site includes many example queries, including those related to health and medicine, food and nutrition, and the life sciences. Examples of health-related queries include information about disease risk, mortality data, medical tests, drugs, and hospitals. Give it a try at http://www.wolframalpha.com/.