Here is just one example of a book from Google books. This is an out of print and out of copyright book digitized by Google and is also available for full download in PDF format.
The idea that, Books like this and many others digitized and made accessible with just a click by Google is so good for all seeking knowledge.
The Google books project is sadly being opposed by some giant corporations like Microsoft and Amazon for some reasons about which I care the least to understand.
I wish Google books good luck and hope they will succeed in the project making me and many others happy.