You’re a modern cheapskate, right? You’re constantly taking selfies, you’ve got no time for the public domain and you can’t take fanfiction seriously. Sit down sibling, because this is the post for you.
Take a look at Smashwords. Smashwords offers self-published ebooks for free. It’s an easy website to publish on, even I managed it. You can filter books based on genre, length, and price, with one of those prices being free. Particularly classy is the ‘Adults Content’ button in the corner. Most Smashword books come in MOBI formats, so Kindle users can enjoy this site.
Project Gutenberg has a self-publishing section. The ebooks come in PDF with font sizes too small for the kindle screen. This site would be great for large tablets, but it needs greater format variety before it can become useful to ereader people. To be fair, this site only started in 2012.
I’m new to self-published literature. Anyone with site or book recommendations can make them in the comments.