Google now has a new competitor -- Wolfram Alpha. Its aim is to "provide a single source that can be relied on by everyone for definitive answers to factual queries". As a mathematician, I find it particularly appealing, because it can be used as an encyclopedia for mathematical facts. For example, if I want to look up the Taylor expansion of arcsin(x), I can do this:
Another example is, I can find the value of the series \sum 1/n^2 from Wolfram Alpha:
This is much more convenient than Google.