LibriVox is a volunteer initative to create audio versions of literature classics. People volunteer to record chapters or books, and then submit these recordings so others may download and listen to them.
To avoid copyright problems, they only accept work that’s in the public domain. For the most part, that means books published before 1923. All of the recordings are freely available on the web site.
Anyone can volunteer to contribute to the project as a reader, and you can suggest any public domain work to be recorded.
If you’re looking for the text versions of public domain works, you can find 17,000 books in the Project Gutenberg collection. This is a similar project that provides these works in text files that anyone may download and use.