And not just math people! Everyone can use it. Billed as a "computational knowledge engine" rather than a search engine, Wolfram Alpha allows you to search for just about anything, from mathematical formulas to scientific principles to historical figures.
Check it out:
Now, if you still want to use a traditional search engine, that's okay too. If you're really feeling saucy, and want to search in two places at once, check out Goofram, which allows you to search Wolfram Alpha and Google SIMULTANEOUSLY!
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.
For more great resources and some thought-provoking analysis of math in the classroom, please read Mathematics Education: A Way Forward, by David Wees.