http://www.wolframalpha.com/It’s essentially a cross between Wikipedia and Google: a search engine for pre-cooked data. It is loaded up with vast amounts of information on many different subjects (particularly math and science), and designed to produce relatively deep information as you type searches in for that information. It specifically makes comparisons of quantitative data automatic and straightforward. It’s intended as a research tool, and aims to be better-vetted than, eg, Wikipedia. It also has Mathematica built into its guts, so you can do complex calculations on all that data straightforwardly.
It’s a classic Internet play, with the sort of grandiose ambition that we haven’t been seeing as much lately. Where Google’s ambition is to organize all of the world’s data, Wolfram’s is to make it computable. It’s still early-stage, and I suspect they'll have scaling problems (since the data management is intentionally centralized) but may be useful for some research purposes…