Whether you like to listen on your iPod or just play the mp3s on the computer or a cd player, LibriVox has all the free audio books you could want. Volunteers read (record) chapters of books which LibriVox then releases for free. Their objective is to make all books in the public domain available, for free, in audio format on the Internet.
There is a very large catalog of books. Choose Pride and Prejudice for instance and you will find several choices to make which may or may not matter to you. There are three different versions of this book, meaning later or future recordings. And you'll notice there are different readers as well. You might want to listen briefly to find which reader voice you prefer. You can download the entire book in a .zip file or chunks of chapters by mp3. Or you can subscribe in iTunes which is a very nice way to do it. (And remember you can use iTunes whether you have an iPod or not.) The entire book goes automatically into your iTunes, but then you manually download each chapter. The first one usually downloads for you automatically. And you can even download CD cover art should you want to burn the files to a CD. In all a very nice site!