Want to share your media library with your best friend? iTunes won't let you transfer your iPod's contents onto another PC, so download Sharepod. This lightweight, minimalist program doesn't require installation, and it lets you manage your library on your iPod through Windows Explorer. You can copy music, videos and playlists from your iPod to your PC and import them into your iTunes library. Compared to Rockbox and Yamipod, Sharepod has the cleanest and most intuitive interface. But unlike the other two, it does not have playback support.
Note: This program is donationware. It is free to try, but the author accepts and encourages donations towards further development. This link takes you to the vendor's site, where you can download the latest version of the software.