You could go to Project Gutenberg. They have been putting 'e-books' on the Internet for years and they have thousands of books available. They're only public domain books, nothing too current. In fact most of them look really dull. But there are some great 'classics' there.
http://www.gutenberg.org
There are authors who publish their books on the Web these days. Sometimes you can read them online, or even download them. I don't know how you'd find them, but I would try googling 'web published book' or 'book published on the web', something like that.