Google History: Fascinating concept. You need a Google API key to try it, though.
“GoogleAnswers is a simple google api experiment. The program tries to answer historical questions with years as answers. It does this by scanning the top 10 pages according to google (from the google cache) for years, i.e. sequences of 4 numbers. The numbers that appear most are good candidates for being the answer.
Of course some number occur more than others on the Internet. 1999 appears more often then 1907, so if we find 1907 as often as 1999, then 1907 is probably the answer. To correct these frequencies differences, I let google search for all numbers from 1800 upwards. This file is available separately. After correcting the frequencies, a new list of candidates is established.”