We've started listening to audiobooks recently, because we spend over an hour in the car several times a week and both kids are prone to motion sickness when they read. My goal is to pick books that they wouldn't otherwise read, are too long for me to read aloud, or are maybe a little advanced.
So far the results have been mostly good (we've listened to the first HP book, Hitchhiker's Guide to the Galaxy, The Hobbit, The Wizard of Oz, the first two volumes of Story of the World, and several recordings by Jim Weiss.) The only "fail" we've had is Robin Hood, which DS9 found too difficult to follow (accent + archaic vocabulary), so we stopped after a couple of discs.
We own some of these, but primarily I've been relying on the library.