Project Gutenberg
http://www./
Good for classic literature as far as the eye can see
Project Gutenberg is a repository for electronic copies of any and all public domain books. The advantage of this is that if you’re looking for a piece of classic literature – and pretty much everything prior to 1920 is public domain – you’ll find it here. The disadvantage is that the database is huge – you can wander for days through the mountains of books listed there. Another minor concern is that some of the lesser-known titles can have dodgy elements in their text, including some unwanted punctuation. However, if you enjoy reading classic literature, this is a definite place to go.

Five free quick picks from Project Gutenberg: The Education of Henry Adams by Henry Adams, Silas Marner by George Eliot, Walden by Henry David Thoreau, Dubliners by James Joyce, and Sister Carrie by Theodore Dreiser.

Amazon’s Free Kindle Store
http://www.amazon.com/gp/bestsellers/digital-text/
A deep mixed bag of free books
Amazon themselves has a free Kindle store which usually contains books that are available for free for a short time as a promotion from the book’s publisher (my own book had this kind of promotion in the middle of last year and hit #1 on the “free” chart). There’s a big mixed bag of books on there, but I found a couple interesting reads just this week – although they seem to no longer be free, just that quickly. Thus, it’s difficult to link to a list of free picks for this store.

Other Sources?
After investigating a lot of additional Kindle resources, I found that most of them fell into one of three categories.

One, they were full of junk. By junk, I mean that a significant portion of the books were unreadable on a Kindle, either due to language problems or software errors or something else. Many of them seemed to be just scrapings of websites, resulting in piles of badly-formatted text.

Two, they were duplicates of Project Gutenberg. I found several sites that seemed to just duplicate what Project Gutenberg was doing, often just collecting piles of Gutenberg books that they themselves liked.

Three, they were full of pirated books. I found a few repositories of pirated books during my search, but I know quite well the work that goes into writing a book and I’ll leave it up to the authors whether or not they want an electronic free copy floating around out there, not the pirates.

Of course, with the three resources above, you’ll have plenty of free stuff to read. If you can’t find something to entertain you in all of that, I’m not sure how to help.