Audible allows you to burn most stuff to CD. I simply made 96kbps MP3s using EAC and LAME.

I have a friend that had trouble playing really low files with Winamp 1.92 (I think). He uses it because it can run as an executable without installing....obviously a very paranoid individual. All books I got from audible are free downloads, so giving him a copy as MP3 doesn't sound wrong to me.

He uses dialup, so keeping the bitrate small is ideal. We just have to find the smallest file size that is still compatible with version 1.x Winamp, his DVD player, and Intel PocketConcert.