I have been an user of Mathematica ever since 1993 and I used to use it extensively for my research as well as during teaching a course on numerical methods. I wanted to write about a wonderful science search engine, Wolfram alpha, but Sachin Shanbagh has already written an article on it. For an alternative view, check out this. Anyway, Wolfram alpha is worth a look.
In case, mathematics or science is not your cup of tea (or coffee) and you are looking for a different sort of search engine (don't be surprised if google hits the Indian market first), look at this - the google matrimonial !