PodLock creates hidden iPod partitions

If you're looking to hide important (read:
embarrassing) files on your iPod, PodLock may be your answer.  By creating invisible, password-protected volumes,
PodLock keeps those situations in which you plug your iPod into a friend's computer a little less dangerous,
embarrassing, or complex.  It also defrags iPod hard drives, manages photos and voice recordings, and can help do some general iPod diagnostics.  It sells for $65 (apparently, it used to sell for $39).