Have you signed up with christianaudio.com yet? There is no cost, and every month they offer a free download. I've downloaded lots of books for free with them - it's a nice way to "read" (listen to) a book while doing housework!
This month's free audio book is J.I. Packer's "Knowing God" - a great book! I've read it before, but would like to read it again. Since I've got a list of books I want to read this year and this one didn't make the list, I'm thinking the audio version will be great - I'll be "reading" it while I do housework or run errands!