I recently did some research on the Internet, including Google books, for books that contain information about my ancestor, Luther Kallam (also spelled Killam and about a dozen other ways). I made a list and downloaded those I could from Google books.
I read about Kirtas Books on Dick Eastman's blog here. He explains it much better that I can, but basically they scan old books on a very high speed scanner. Once it has been scanned, it can be either downloaded or a copy of the book can be purchased.
Tonight I ordered two soft cover books, History of Susquehanna County and The Centennial of Susquehanna County. Download fee was $1.95 each and a soft-bound copy was $8.05 each. With postage the order for the two books was a little less than $30.00. So for $15 a book, the price of a paperback at Barnes and Noble, I will have my own copies of out-of-print books to refer to whenever I want. Can't wait to get them!