Our school library is starting an audiobook collection, as the start of a digital collection, and we were thinking to start with some creative commons and public domain titles.
I've mentioned before about some sources we use for free content, but I wanted to be a little more specific about some of the resources we're looking at for starting the digital collection.
Librivox - volunteer-read public domain works
Spoken Alexandria Project - creating audio books of creative commons works
Podiobooks - free serialized audio books
Lit2Go - a free online collection of audio stories and poems
Project Gutenberg - human read public domain audio books
X Minus One - a series of science fiction radio plays, not technically audio books
Cory Doctorow - an author who creative commons licenses his works, a number of them have been recorded as audio books by him or by fans