From the American Action Fund for Blind Children and Adults website:
In 1997 the AAF (American Action Fund for Blind Children and Adults) started this program to provide blind children a free Braille book every month from a popular children's reading series. The books are for the children to keep and collect for as long as they want them. The titles published every month are the same titles that are available in bookstores and public libraries everywhere. In the past ten years over one hundred seventy titles from popular children’s reading series were distributed to thousands of blind children.
As we send the 2012 titles out each month, the corresponding BRF files will be available here. You will be able to download your free Braille books electronically by right clicking on the file or using the applications key to choose "Save Target As" in Internet Explorer or "Save Link As" in Mozilla Firefox.