M3Unify s a flexible M3U playlist creator and file exporter that will allow you to load a USB thumb drive or SD card with copies of your iTunes songs the way you and your audio player want. M3Unify can archive playlists and audio files to a folder, volume or portable media and includes options to create Artist/Album sub-folders, rename files, convert to AAC or MP3, and more.
This latest version adds the ability to encode to MP3 (via iTunes), correctly adds image data to AAC-exported files' metadata, and has minor performance and UI fixes.
For OS X 10.8 and later. M3Unify is $5.00, but free to use in demo mode with a fifteen track limit. This is a free update for registered users.
More information, video demo and download is here.