"I firmly believe you should have the right to transfer your music with any application you like and if this requires software which circumvents DRM (digital rights management), then I don't believe this is ethically wrong," Fisher said. "I trust our users to use this freedom responsibly and to not steal music."The author claims iTunes uses a lot of system resources while Winamp works a lot faster. More details about the plugin at Wired. The plugin can be downloaded here.
Winamp ml_iPod plugin adds iTunes functionality

A Winamp plugin called ml_iPod gives iPod users the ability to bypass iTunes and manage their music collection in Winamp.