Google and newspapers are bringing a LOT of history online soon in the form of archived newspaper pages - billions of them - that will over time flow online, giving us one of the best pictures of history across many cities and a long time period that we have ever had.
This could be a researchers dream in that local news often has information you can find nowhere else. Things like Police and Fire reports, obscure local political quotes by major politicians (hmmm - that's gonna hurt sometimes), and much more. I'm really looking forward to this project!
Official Google Blog: Bringing history online, one newspaper at a time