Offering something for free doesn’t guarantee people will make the most of it. The latest example: eBooks distributor OverDrive says providing DRM-protected audiobooks to public libraries in the WMA format has discouraged iPod-centric users so it is expanding its catalog to DRM-free MP3s as well. The new program starts today at the District of Columbia Public Library with five more libraries to follow. It’s a small number compared to OverDrive’s arrangements with about 7,500 libraries to distribute its catalog of 20,000 DRM-protected digital audiobooks.

The MP3 audiobooks are tied to specific libraries so users will still need a card from their local branch. And even though MP3s are not copy-protected, users have to agree to borrowing terms. When the lending period is over—different branches have different terms—access to the software expires and a prompt is sent ordering users to delete the files. So far, audiobooks have not been a major piracy target in the way that movies and music have, something Random House has pointed out when discussing its DRM-free audiobook sales. Release

• Ebooks Catalog OverDrive Adds MP3 Audiobooks; Borders Signs On First