Once you visit Librophile you can start using its search option to look for ebooks you might have in your mind. If you are lucky enough then it might be in the free section. The website's interface is user friendly and it wont take you more than a couple of minutes to get yourself acquiatined with surifng its content.
Librophile allows you to browse the title one by one using criterien such as books genre and popularity. When you find the audio book you want to read then you have the options to either download it chapter by chapter or in one whole zip file. To stay updated about Librophile's recent released you will need to subscribe to their iTunes feed of the audio.
Head over to Librophile and give it a try.