Project Gutenberg (http://www.gutenberg.org) practically invented the e-book in 1971. The first e-books were text typed by volunteers. The process was slow and tedious. They added not value to the text on the screen. Only public domain books were in the collection.
For more information about the project read:The Project Gutenberg EBook of Project Gutenberg (1971-2008), by Marie Lebert. Toronto, Ont., NEF, University of Toronto & Project Gutenberg, 2008. Available online: http://www.gutenberg.org/files/27045/27045-8.txt
In August 1997 Gutenberg had 1,000 books online and by March 2009 there were 29,000. They add about 340 books each month. Now it is possible to purchase a 1 terabyte hard drive for less than $100. That is enough to store about 1 million books, which is larger than most research libraries.
Currently e-mail are sold in a variety of formats that imitate the printed page. They are sold by commercial publishers, government agencies, and non-profit organizations. I am planning a larger article on the use and place of e-books in the library and in the individual private library. If you have any comments about how you use e-books either for pleasure reading, learning, or scholarship, please let me know.