That's a big advantage I forgot to mention. Amazon has done a remarkable job of making out of print books and books in the public domain available on the Kindle for a buck or two, or sometimes for nothing. Often, these out of print books are not available except through the Kindle. As an example, last Summer I had an itch to read about the Boxer Rebellion. Within ten minutes I had downloaded three first hand accounts, long, long out of print. I could not have had access to these books any other way except through the Kindle. Another example would be WWI first hand accounts, many of which are esoteric, and of which there are dozens and dozens available on the Kindle.
Tons of out of print old stuff here, even the 1790 census . Many older herb books it may take awhile to find what you want but more than likely it is here! Also they are all free....
http://archive.org/details/texts