Smart AudioBook Player - Smart AudioBook Player app comes up with features to help you in casting all your audiobooks to Chromecast enabled devices so you can enjoy them with your friends and family members.
LibriVox - free public domain audiobooks
Voice - Convert texts to audio files easily... Write your text, click export.
Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
Mobilism.org - A home for book lovers, app enthusiasts, and much more.
Material Audiobook Player - Open Source Audiobook Player for Android