They are a young adult series of books, starting with the first self-titled book. If you know of them or know someone who likes them (and audiobooks), odds are the sequel to the series is of interest to you. If you pre-order the first book in the sequel series called Dragonwatch and use a promo code, you get all five of the original Fablehaven series audiobooks as downloadable mp3s for free.
You pre-order from Deseret Book's website, use the promo code WC1712, and you then can download each book as a zip file. The files can sometimes be haphazard in their organization (in a different series I had one book that was one mp3 per disc and another that was nearly 200 mp3s because each was 3:00 or less in run time) but still a killer deal.