WolframAlpha
Now that I am on the topic of search engines, I'd like to mention a new generation of search engines which are more sophisticate than a tool finder. They are called computational knowledge engine or as I would like to call them, they are search engines which are using semantic web algorithm to locate information. WolframAlpha is one of them and I believe it will have a lot to offer. One important aspect of these search engines are their capabilty to undrestant natural language. For example, go to WolframAlpha and type this question - Where am I.