Every now and then the Economist publishes interesting graphs where they show how the count of the word 'Recession' in selected news publications correlates with the actual occurrence of an economic down turn. I always found this fascinating and used to think about all the cool stuff you could do if you had the actual counts of all the words in the all the news. And then I joined Google. Oh boy.
I remember talking to somebody from the news team and asking about this. Oh, well, we have that data around somewhere, the answer was. Using Googles Mapreduce it was actually quite simple to run over this data and extract the counts for words in the news over time. I threw together a quick http server that would actually plot the data and send it around the company. People thought it was pretty cool. Later I added the labeling of the peaks using the headlines of the news and some people started saying things like this should be launched on labs.
Then I met up with the guys doing something similar, but based on the number of times people searched for a certain keyword and we decided to combine the efforts. Oh and a designer had a look at the thing (my demo might have been cool but was also rather ugly). Yesterday the thing launched on Google Labs as Google Trends.