An interesting talk about the correlation of Google search and Wikipedia page views to the rise and fall of stock prices. It also extends to the predictability of the stock market indices in general.
Google Talk on the book What’s Behind the Numbers by the authors.
Note: It is 1 hour 16 minutes long.
I choose this video because it is a great alternative if you find reading the book is too time consuming.
If you are interesting in trading stocks (and the indices), their work can convince you stop believing in many myths produced by the Wall Street marketing machine.
The question and answer session after their presentation is also a good one.