For those of you looking to download music from an iPod to a computer using Windows XP, Windows Vista, or Mac OSX, here's all the tools you'll ever need.
MAC OS X
To download songs from your iPod to your Apple, download Senuti. Senuti (which is iTunes backwards, btw) has a GUI interface that allows mac users to download songs directly from their iPods into iTunes.
Tip: Add the Senuti dmg to your iPod in "disk use mode" and you can take Senuti on the road with you for when you're visiting your friends and family.
Windows XP and Windows Vista
To download songs directly from your iPod to your Windows PC, download EphPod. The EphPod interface allows you to browse your iPod and download songs directly to your iTunes.