Free audiobooks available here - all old classics and public domain stuff, hasn't been updated in a long time. The free versions are fairly poor quality but you can pay for higher quality versions and also buy in bulk on CDs or DVDs. This is where I had my first taste of audiobooks before audible.com even came into being. Love the Edgar Rice Burroughs Mars and Tarzan series!
http://www.audiobooksforfree.com/home