For a biography that I am writing I relied on obscure books (from the 1870s-1880s) that showed up in targeted searches. They provided relevant information, insight and further references. I do not have access to a university library, but thanks to Google Books, I was able to plow ahead from my home computer.
I wish Google would continue to digitize books and make the full text searchable and readable. Maybe the authors’ interests could be protected some other way — by disabling the copying of text or by requiring a payment to enable text copying.
I also wish Google would digitize world newspapers and non-English books.