Capo lets you export pitch- and speed-corrected audio for use in your iPod, so you can practice your favorite music while you're away from your computer.
You can also export only the looped portion of a song, and load that onto your iPod for seamless looping.
Capo exports files using the MPEG-4 AAC audio codec by default, and can optionally export uncompressed AIFF files for higher quality output. You can choose the format from the popup button that's displayed when you're prompted to save the exported audio.