Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
Audiobook Builder - Audiobook Builder is a software that enables users to turn their audio files into audiobooks which they can sue then on their iPhone, iPad, or any other Apple devices.
LibriVox - free public domain audiobooks
AudioBookBinder - Got a lot of audiobooks in MP3 format and would like to listen them on your iPod?
LearnOutLoud.com - LearnOutLoud.com is the web's largest resource for audio & video learning.
UkeySoft Audible Audiobook Converter - UkeySoft Audible Audiobook Converter is a popular AAX/AA to MP3 converter, it not only can remove DRM from Audible books, but also can convert Audible AA/AAX audiobooks to MP3, M4A, AAC or FLAC with 100% original quality preserved.