My family and I enjoy listening to those good old radio shows of the 1930s-1950s. And lo, and behold we have made a wonderful discovery! You can download radio shows that are in the public domain for FREE at: http://www.archive.org/details/oldtimeradio.
They have many wonderful selections, such as:
The Adventures of Sherlock Holmes
The Roy Rogers Show
Cavalcade of America
American History Through The Eyes of Radio
KIBM Presents Christmas Playhouse
Lux Radio Theater
Try searching around on the site for something you love that is old and classic (example: Bing Crosby, Jimmy Stewart, Shirley Temple, Deanna Durbin, etc…), as they have more then just radio shows. They have music, movies, and TV shows too.