For a limited time, you can download a free audiobook of Henry David Thoreau’s Walden read by Mel Foster. This is the commercial version of the book, which retails for $23-33.
The unabridged audiobook is provided as MP3 files, which you can simply drag into iTunes, and then sync to your iPod or iPhone for listening. You can change their Media Kind to have iTunes treat them as audiobook tracks, or with a little more work, you can convert them to a single audiobook file.
Note: If you don’t already have one, you will need to create an account on Tantor Media’s site, which will sign you up for their newsletter where, among other things, you can learn about future free downloads.