Here is a website worth visiting. The e-books you can find here are fiction, adventure, study, history, crime, etc. You also can find many novels, short stories and study books. Though don't expect to get the Harry Potter and the Deadly hallows in this website because it only showcase the books that have no copyright and are also old enough to have dusts in it. Look at the list of categories you can find in the website: http://www.gutenberg.org/wiki/Category:Bookshelf
Though there are no new books there still are some of the great stories and novels. There are different formats like html, plucker?, EPUB?, plain text, MS Lit for PocketPC, Palm Database, etc to choose from.
Hey I just went more into it and not just reading books but also listening books are there. Now ain't that cool?