The iPod Touch to iPod Video hack makes dramatic changes, with lovely a Touch-style Now Playing screen and menu icons. You don?t get Cover Flow from either hack, but you do get a very cool (and reversible) overhaul.
Download and unzip the hack, and then download the free iPodWizard utility, which makes it possible to load third-party firmware onto your iPod. If things go wrong or you don?t like the new interface, you can return to iPodWizard and click the Downgrade Firmware button to restore your iPod?s original firmware.
Note: This link takes you to the vendor's site, where you can download the version of the software that's appropriate for your iPod.